I use an 8" record power with the white wheel, it does the job just fine, I also use the sorby jig system with it as I enjoy the single pass precise sharpening that gives me. The advantage of an 8" over a 6" is the larger diameter gives a shallower bevel (hollow ground) plus the wheels will by virtue of that last longer. I would recommend the 8" if that is your budget. If you do get it be sure to mount it in such a fashion as to give the rubber feet the freedom to absorb the vibration, if you bolt it down tight the thing will rattle everything in the workshop, but mounted properly it it runs fine.