The THC and powered Z are more for cut quality and consumable life than anything else. I have seen the quality difference with and without and I would not want to make a part for my customers without it. But I dont really have a plan to use this machine for profit at this time.
So for now I plan on a manual Z. Once the bugs are worked out I may just replace the RAMPS with some gecko drives and a Proma THC and run it with Mach3.