I believe you are talking about my post a few days ago here.  Unfortunately, I'm still wondering the same thing.  I haven't printed anything since I posted, and I'm waiting on my new stepper driver which should arrive today.

I wouldn't think so - eg see
http://reprap.org/wiki/Triffid_Hunter's_Calibration_Guide#Layer_height.2C_Extrusion_width
http://hydraraptor.blogspot.com/2011_03_01_archive.html

The important parameter is layer height: you want it at most .8 of nozzle diameter, to squish the plastic to get a good bond, and the rest sort of follows..

In fact, theoretically the .35 nozzle was inadequate (or, marginally adequate) for .3 layer height, so it's a good thing they switched to .4.

This also explains why some ppl recommend printing at smaller layer *height* (eg .2 instead of .3) for better strength (one way to get higher width-to-height ratio, I guess..).

Ive been using .45 width recently to get a little better layer strength. Probably just use whatever is working:P

Somewhere I also remember reading that solidoodle switched nozzle sizes on newer machines (though I don't remember which direction the switch was in :-).

I do have a relatively new SD2, so now I'm all confused and wondering if all those settings I have that say .42 should really say .48?