I have three grinders,a cheap Aldi 6" one,been in use for getting on for 20 yrs now,as said a light touch works best,it also makes the wheels last a lot longer as well as the tools,the second grinder is a homemade slow grinder with 8" wheels again from Aldi,spins at around third to half the speed of a standard one,it has been in use for around 15 yrs,the newest one is the cheap wet grinder that Axminster used to sell,modified with wood to get a better position for the toolrest,I like this one for touching up the tools on the fly,had to dress the stone before use as it had a poor surface when bought new,thinking of getting a tormek 8" stone for it to see if it gets a finer finish on the tool edges,but saying that being dressed with a fine stone seems to give a fine edge,so swings and roundabouts I think,cheers,
Eric.