The G8 is one of the Suehiro 8k stones - they also make an AlumOx one.
I have the Suzuki Ya 400, 1k, 2k, 4k 8k - I use the 1, 4, and 8 most often. IDK what the manufacturer is, they aren't saying. Only that they do not have a retail outlet and are not available in the US except through their (S/Y) shop. For carbon steel woodworking tools they are crazy fast and make an incredible edge. They work great on the vast majority of stainless as well, but as the carbide content goes up they predictably begin to lose a bit of effectiveness. If I don't have any idea what steel a knife is, these are the stones I use.
Yes, 3M belts. I only use them for sharpening, no primary regrinds or heavier work, always edge trailing, fairly low FPM. The 125 micron cut real fast and last a looong time in that role. If you get into the 45 and 9 micron they don't hold up as well, but I do all my finishing on stones and Washboard anyway. I've done a couple of convex hair shears using the full progression (125, 45, 9, and leather belt with Washboard compound) - they do a great job.
In my use they are very economical - one of the few advantages of the 1x30 belt grinder w/ variable speed.