I didn't mention HF because those grinders are junk.
A couple of years ago a friend and I were using grinders to fine tune notches on logs, I had my 7-8 year old Makita he had his brand new $20 HF grinder. He was so thrilled on what a good deal it was.
He got maybe 3 working hours (if that) out of it before burning it up.
He exchanged it and burned that one up too (this was getting funny). Third times a charm??? Not!
Finally he came back Porter-Cable and actually got some work done.
It is a hit or miss on their stuff, along with how you use it. If it is continuous use, any tool can fail due to heat build up on the windings or brushes. QA has gone down a lot on every tool out there, regardless of the name. Also just because the tool is more expensive, does not make it better.
Personally I would have used an air powered tool for doing those notches on the logs, vs. electric powered.