i have both the 3'' and the 4'' capital internal cutter.
if the guys don't have big arms / forearms, they will when they finish
it works much easier with some wd40 on the wheels.
the great thing is, once you set the depth, it doesn't need to be adjusted again. you're setting it 1/4'' higher than the finish floor, correct
the problem with a grinder is the cuttings/ fines/ sawdust
nothing like cast iron dust all over the place and a little bit of water. you will be buying floors if they are finished floors. not to mention lungs
the cutters do a good job, but as dog noted, why not prefab them to the proper height in advance? sure the cutter will cut them to the exact finish height, but the time and muscle involved is tremendous. figure on at least 3 minutes each going room to room. i can't picture more than 100 a day as the guys arms will be burning
good luck. let the apprentice who wants a gym membership use them.