I have fully "cajunized" mine myself and added a few things over and above what they offer in their "pro-grade" package. I have done the firing pin, short reset kit, hammer, extra power sear spring, trigger with the set screw, blue 13lb hammer spring, gold 15lb recoil spring and SS guiderod. I also have their sights installed which I think are made by dawson. Quite honestly it's a night and day difference over a stock pistol and I use it for some informal comps.
As far as must have upgrades, the short reset kit and hammer spring are it. Everything else makes it better, but IMHO the gun needs those upgrades bad. The set screw trigger is not really needed with the SRS kit and hammer as that takes basically all the overtravel out. The SA trigger is better than any stock gun I've tried including some stock 1911's but isn't as good as a perfectly worked over 1911 trigger. It is truly remarkable for drop in parts and rivals Geisselle in that regard. In fact, my P09 with cajun parts feels a lot like an Enhanced Geisselle with the light take up then icicle like break.
If you buy the CGW gun, you will not be disappointed.