That is awsome to know that GM will work for the dewalt.
Ok, so, from working in the tile/pool/plaster industry, we tend to abuse the living crap out of angle grinders.
I've burned up 2 milwaukee, 2 of the Makita's and 4 dewalts. Mind you, the dewalts have out lasted any other brand used. I just happen to use the dewalts more now. Milwaukee lasted a month, makita ran GREAT for the month or so, before the bearings exploded. The dewalts lasted 6 or so months before one's hand switch melted, one's gears froze, ones chord shorted, and the other...well..we don't know yet.
I still run dewalt because they last "longer" than the others.
And Crash, Fastenal does waranty work for dewalt, and I would imagine they can get parts for you. 
