David Weaver
similar comments, except mine makes a big spark pattern.....I think the open matrix on them and large grit makes it so that they are probably technically a hard wheel, but the big bits and holes come apart easier.

The sparks are fewer but much larger. Sort of like comparing a string of little mini christmas lights to a string of fewer of the old 7 watt bulb types. Something slightly different in mcmaster's wheels vs. the ones at victor, maybe - mine

If they're relatively cool running on a high speed 8" grinder, they should be easier yet on a 6" machine.

Not that you can't burn an edge with them on the high speed 8 if you lean into them, but there's no need to do that (the same is true for CBN - my first ever test with the CBN Wheel was to flip the bevel on a 1/2" timber mortising chisel that someone had on the wrong side of the tool - it was bright orange by the time I ground off a triangle with a base length of over an inch. and the CBN wheel held up fine (which was what I was really looking to test).