Like many here, I have a variety of machines. Different wheel sizes, different manufacturers, different switches, different power requirements. I am not a shop-owner, just a hobbyist.
From a safety standpoint, I will say I agree the paddle is the safest. I'm retired, and a couple of times I've had a item of clothing get grabbed by a wire wheel, and having to frantically pull-out of the duplex outlet or the extension cord the plug isn't as-quick as releasing the appliance for an immediate shut-off. I will say that each time it's happened, it's been my fault that I let the grinder get too-close to my shirt or pants. The paddle switch gives you that measure of safety where the power discontinues as the motor tries its best to climb towards your face or the family jewels. The paddle switch helped me to reach retirement, without 'retiring' me!
I have two big 120 V Milwaukee two-handle 9" grinders. I have a Dewalt, an orange Harbor Freight, a grey Harbor Freight, and a couple of Milwaukees, all 4 or 4.5" 120 V grinders, and a Craftsman C3 19.2 V cordless. I have different wheels on them so I don't waste time switching them out. Each has a place.
From reading about the Metabo and the Fein tools, maybe some-day, but for now, I'll make-do w/my present eclectic mix.