I print at 30 for everything that matters and I only go up to 50 even for a travel speed. This is about the speeds that xyzware had for it's "excellent" output options.

What I've noticed over the slicers that I've tried is that xyzware does "fine" IF it can slice the object at all, Cura does better on fine details and is faster but has poorer supports than Slic3r, and that KISSlicer is somewhere in between. I've also tried Mattercontrol and depending on which slice engine you choose, seems to match the output of Cura or Slic3r's native output.

Out of the two "big" slicers left I still want to try is Simply3d. I'm just waiting until they have an option for "trial", so that I can test and see if for what I do it would actually matter. My prints are not done for artistic reasons, which means that as long as the item prints and I can get the dimensions correct I'm satisfied with that.

I'm running my printer on a modified version of "E" so that I don't have to mess with a cartridge resetter. I print directly from the printer off a Flashair SD Card, so that I don't ever have to hook up anything to the printer to send prints.  All of this could easily be "upgraded" by installing repetier and Simply3d, but at the moment I'm satisfied with the results I get.

Also it's the end of the file that Cura creates by default that causes issue's, not the start. What it will do is not "finish" printing and home / lower the build plate.

This in the start code ...

;Filament used: {filament_amount}m {filament_weight}g
;Filament cost: {filament_cost}
;M190 S{print_bed_temperature} ;Uncomment to add your own bed temperature line
;M109 S{print_temperature} ;Uncomment to add your own temperature line
G21        ;metric values
G90        ;absolute positioning
M82        ;set extruder to absolute mode
M107       ;start with the fan off
G28 X0 Y0  ;move X/Y to min endstops
G28 Z0     ;move Z to min endstops
G1 Z15.0 F{travel_speed} ;move the platform down 15mm
G92 E0                  ;zero the extruded length
G1 F200 E3              ;extrude 3mm of feed stock
G92 E0                  ;zero the extruded length again
G1 F{travel_speed}
;Put printing message on LCD screen
M117 Printing...

and this in the end code...

;End GCode
M104 S0                     ;extruder heater off
M140 S0                     ;heated bed heater off (if you have it)
G91                                    ;relative positioning
G1 E-1 F300                            ;retract the filament a bit before lifting the nozzle, to release some of the pressure
G1 Z+0.5 E-5 X-20 Y-20 F{travel_speed} ;move Z up a bit and retract filament even more
G28 X0 Y0                              ;move X/Y to min endstops, so the head is out of the way
M84                         ;steppers off
G90                         ;absolute positioning
G92 E0
M84     ; disable motors

Will print correctly from the SD card with Cura if you use something like notepad++ to change all the G0 statements to G1 with the search and replace all function.

Have you tried netfabb to repair the STL?  Can you share the STL so I can try here for you?

It's not that there is a problem with the stl file, it just happens to be such a size that slicer freezes up trying to slice it, cura tends to do just fine with it. The only time I've actually got it to slice in xyzware it projected that it would take 22hours to print, and that was set to 10% infil and fast speed, cura will only take 7 hours.

Have you tried netfabb to repair the STL?  Can you share the STL so I can try here for you?

He did say it was a commission, so it is doubtful he can share it.