I didn't know that HF sold chainsaw files.... %-P I have the HF chain grinder, and it is a VERY basic and cheap plastic item - emphasis on the cheap, considering that it's often on sale for $30 or so... From pictures and other discussion that I've seen, I'd say the Northern unit is better (and some of the guys on Arboristsite mod them to allegedly make them as good as the Oregon units, at considerably less cost) but it also costs a LOT more...
IMHO the HF unit is good enough to deal with a badly rocked chain, but if I want to get a SHARP chain, I break out my files...
Gooserider