I have three M18 fuel 4.5" -5.0" grinders (5" cutoff wheel; 4.5" sanding disc, 5" grinder wheel) 

I have just recently purchased the bigger M18 Fuel 6" grinder, once I researched that one of our hardware stores, actually sold a 6" cutoff wheel {one store does} = I had some areas, where a NEW 5" cutoff wheel couldn't cut deep enough. I've used it very little, so far. It is a bit bigger and heavier, but will work for what I need it for.

All are paddle switch style.

Note: I don't change disc, I grab a whole different tool, with the correct disc already on it. (I'm too impatient, to constantly swap disc, back and forth, when building or modifying something)  Same reason, I have a whole bunch of air-operated die grinders, with different bits installed


I think the 6" might get a little heavy, if you are doing some "one-handed work", verses, like I do with the smaller, normal-sized 4.5" sanding disc or 5"grinder wheel.