which the main advantage is that you can get higher detail prints. as per their blurb "New functionality in Simplify3D will automatically adjust the amount of plastic that is extruded from the nozzle to create smaller or larger extrusions depending on the shapes you are trying to print. This is extremely helpful for thin or tapering shapes, allowing you to print new features that were not previously possible with a fixed extrusion size."

so for example the tip of a rocket nozzle or a fan blade will be more precise.

this also gets used in the dynamic gap fill.  "Thin walls and gaps can now be filled with a single dynamic extrusion that is automatically adjusted to fill the available space. Even if the thickness of these walls are constantly changing, the software will ensure the gaps are perfectly filled adding strength to your model’s interior. This also provides a significant print speed improvement versus previous gap fill methods"

At least that is what I think he was trying to discuss.

Because the extrusion is smaller it can be squished to the bed more without stripping the filament.  I truly don't understand completly why it works as well as it does but I get fantastic results this way.

I have a theory.... Atmospheric pressure aka suction cup effect.   I've recently gave up on ever getting good adhesion on my printer so before i trashed it.
I did a dramatic thing..i trashed all my slic3r profiles and started with everything hardcoded to .4mm(my nozzle size)and worked my way through about 5-6 independent tuning guides. 

Doing this I learned a couple of things:
1.  Don't use percentages for any value except maybe speed.   Most percentages are based on layer thickness.  Hardcoding values allows you to change layer thickness without screwing up a ton of other stuff.
2.  What most of the numbers ACTUALLY do.

It is a long drawn out process I have to recommend to anyone serious with 3d printing. (thanks again Wardjr for your feedback on that thread)

While printing my hundred or so calibration prints i ran across this effect you mention.  I have always noticed that detachments almost always occur from edges.   When i was printing with the fat .4-.8mm first layer in my journy, i notice the detachments were starting to occur from places not adjacent to an edge.  I reduced the width to .2mm and i got a solid mostly airtight layer. after i made this change my prints started sticking wonderfully. 

Therefore my theory is that not only do you have the mechanical bond for the first layer, but it acts like a suction cup as well ...

If you are interested my final settings were something like:

all extrusion widths .4 except solid infill which is .2
support is .3
3 shells and enough top and bottom layers to give me about .9mm worth of plastic based on layer thickness.
first layer is .15mm

I calibrated my bed to .0608 mm (like third thinnest leaf on my gauge.  make sure they dont stick together,  measure the leaf with a micrometer/caliper to be sure).  that gives a final first layer thickness of about .2108 mm

Now I've tried extrusion widths as low as 0.24 for the first layer with a 0.4 nozzle, but I found this trick only worked well for some prints with a 0.4. Sometimes it would stick like glue, other times the plastic would get pushed up off the bed. With a 0.6, I don't have much issue with this trick and it works well. I think I ended up extruding the first layer at 0.36 with good results but I can't remember exactly and I can't check my settings.

I do it all the time with a .6 nozzle and can get down past (but choose as my min) .36
Utilizing smaller extrusion widths (Than nozzle diameter) is a fantastic way to increase print speeds while maintaining quality.

This is a reassuring post.

i remember jagowilson suggesting the same.
But I tried 0.2 mm thickness for first layer, and it doesn't stick to the bed at all.
Are you maybe squishing it also quite a bit?
This is interesting, any ideas why this improves adhesion? I've been having serious adhesion problems lately (everything I print warps).

I didn't quite get what you mean.

I guess this means it's safe to play around with the numbers.

Okay, so this is what I tried.

Printed rectangles and circular buttons only so far, no overhangs or complex shapes.

Okay, so with 0.2mm layer height, 0.2mm External perimeter width and 0.2mm top solid infill I got a pretty good rectangle. The top is like it wasn't 3d printed. It's not 100% smooth either, there's a tiny bit of texture to it, but I couldn't see the lines

Same with setting the values to 0.1 mm.

Then I went ahead and tried 0.05 mm just out of curiosity. I got some smearing of the plastic in places and in places the plastic had brown spots. I think a sign of over extrusion and plastic burning by contacting the hot nozzle too much or the z motor not moving the bed down enough for each or some layers.
My hotend temp is 215C.

I'll post photos when I find lens for macro photos. These details are really small for my camera.

In general the results are pretty satisfactory so far. Thanks everyone for the input.

One question I have now, is there a point in me getting a 0.2mm nozzle if a 0.4mm nozzle can do 0.2mm already?

No offence taken.
I'll search deeper, but so far I've only found posts along the lines of "minimum extrusion width can't be lower than nozzle diameter", but I've just seen with my eyes that it most definitely can.

I do it all the time with a .6 nozzle and can get down past (but choose as my min) .36
Utilizing smaller extrusion widths (Than nozzle diameter) is a fantastic way to increase print speeds while maintaining quality.
I always print my 1st layer at about half the nozzle diameter this seriously improves adhesion to the bed. I do the same for the top layer to improve quality.  My outer perimeter is about 75% of nozzle diameter to improve detail.  Then go slightly over nozzle diameter for infill.  Of course there is support which can be a difficult one to dial in but can dramatically improve removal if done correctly.  Take some time and play around with the numbers to see the different impact.

cant hurt anything to try and unless using PLA with the 0.35mm nozzle or setting extrusion temps too high or low for material used, this wont cause clogs. so experiment and let us know what you find works best for items printed.

rule of thumb seems to be nozzles 0.4mm and smaller can act like a Nozzle up to plus/minus 0.05mm dia, while Nozzle sizes 0.4mm to 0.6mm etc can have a span of plus/minus 0.1mm dia. thats why the steps in sizes available reflect this.

well excuuuse me.
What did you type in the search box that you could find anything which I didn't?

I most certainly did not mean to offend.  I was simply in a hurry and thought you'd rather search than wait for me to find a link.
This is one of my favorite topics because so much of it is overlooked or otherwise not experimented with.
When I get some time I will try and find some links but for now if you search "extrusion width" you will get more than you want but dig in about 5 or 6 pages where most of this is covered.