OH No I'm not selling - Now  It's a 167 flat bed  my problem was it's too fast  way Too fast  - or was. 
400W or 500W the servo motor has it under control  I can single stitch - no really- tap the pedal and 1! stitch   Before and tap the pedal  presto three INCHES of stitches. 
so I had to do a lot of wheeling   I'm sure a professional could have opperated this much better  but I'm not a professional  not now not ever.  
I'm a blacksmith  and for light work I use a 2 pound hammer.  so subtle is out. 
I can only say if you have doubts about getting a servo  just do it ,  
I have the slower of the two Artisan sells  I dont do long runs . 
Thanks though. 
 Chuck