For hollow grinds :
An 8" serrated gets there quick full speed, both profiling and cutting in the initial bevels. After Ht, I use the 10" or bigger smooth wheel for the finish grinds. The smooth wheel seems to like a medium speed with lighter pressure. The smooth wheel seems to want to jump up and over your flats or spine at a certain point if you're not paying attention...it's a 'feel' thing. It's most likely due to contact with more surface area and pressure. I do this free hand and don't know if it would be any better with any of the grinding gizmos. Watch out for belt bump with the higher grits on a smooth wheel, the micron belts don't seem to like it.
Rudy