Take a page from Mountain bikers?
Those guys will review not just bikes but parts of bikes, and accessories like safety equipment. I found this site incredibly useful in figuring out just _why_ I should choose one part over another:
http://www.mtbr.com/reviewscrx.aspx
All reviews are by users, not professional writers, so there is a nice spread of reviews from the well thought-out to the knee-jerk angry rant (this sucks because it didn't work for me, wah wah wah).
Things like price paid, where & when purchased, user level (arborist, climber, logger, home-owner), type of wood cut, # of cords cut (if applicable), length of bar, type of chain, perceived fuel economy (admittedly a tough one) could all factor in. It could easily expand to cover other parts like aftermarket bars, chains, oils, mufflers, pistons, muffs, hard-hats, glasses, boots, chaps, tools, paints (for the resto fans) and so forth.
Being able to sort something like 50cc class saws not just by overall votes but by number of reviews is also helpful (for example, click on wheelsets in the above link, then click on the column headings to sort). It's telling if a saw has five stars based on one review (useless), versus a rating of one star based on 100 reviews (useful).