I havent' read all the posts, but here's some stuff I've learned.
KBAC27D....110V or 220V input easy to switch voltages, just dont plug it in to 220V untill you switch the jumper in the box. It will run up to 2hp motor on 220 or 110, does suprisingly well on 110.
KBAC29.......220 volt input, can run 2hp on single phase input 3hp on 3 phase input.
I'll take a 2 hp 1725 motor over a 3hp 3450 rpm motor. This depends on the rpm range you will be running. If you plan on ever running a small wheel attachment, forget about the 3450rpm, MY OPINION, from my experience.
There is a new controller out from KB that will do 3hp on single phase power. I think it's the KBAC29-1P, the only problem with 3 hp/3450 rpm motor is you lose a LOT of torque at slower belt speeds (my experience).
Also whatever VFD you use, I would add a fuse to the power in. The 27d typically calls for 25amp on 110v, and 20 amp on 220v. It's real simple my grinders use the same fuses as my truck, and I still get them from NAPA. It's cheap insurance.
Don't talk on the phone, while checking jumper settings, with the grinder plugged in......nothing like near electricution while explaining settings to prove ones intelligence