I have two KMG's side by side both are vari 2 HP, I once bog them down to see what would happen. So with a 10" wheel fresh 60 grit blaze, glass's face, mask and gloves flipped the switch and set it to full power and stepped into the wheel pushing with all my might. About 10 seconds later the machine's VFD tripped and shut down the motor wow man you should have seen the grind line
Might point you can bog it down but try to picture a person ready for war and completely out of control, anymore I rarely turn my grinder above 30 % for grinding hollows for edge work I will go into the 80% at times. As far as the small wheel be careful of turning the grinder up to high and that small wheel attachment will blow up in your face.
So 1.5 and 2 hp motors work just fine IMHO down the road I would like to have more power but for know I am happy.
Now about the MAP ARM pure genius I tell you, I have 2 of those as well and always make the comment when grinding how glad I am to have them. I can do some things with the MAP arms that you can not with a conventional rest.
Now the MAP arms use for each maker is as diffenerent as the knives we make, so I cannot help you there but if you like it you will find more and more cool things you can do with it.
So 3 horses in which you will only really ride on maybe 1 or the MAP arm that you can use in all phase's of your knife building?
"Thats what I think"
Spencer