My first question to you would be:
Do you need the extra 50+ lbs capacity?
Next consideration, as you pointed out, is the extra $2K
If you're smoking large amounts on a regular basis you should consider the FEC.
I've cooked (commercially) on both the FEC100 and a CS 150. If it came down to one primary reason of preference, I like the fact that the FEC comes up to temp in minutes and recovers very quickly when the door's opened. I also find pellets a lot easier to deal with.
Probably a minor aside but if you ever get the bug to enter a competition, the FEC is a sanctioned smoker; electric smokers are verboten