Here is one of the reviews for the SAP Spitfires. I think this is the one I read that helped me decide to go ahead with the mechanicals.
shewe has a good point about less to go wrong with fixed blade BH's.
But check out this review if you are considering mechs. Here is the link:
http://www.hunting-fishing-gear.com/review-display/2695.html
There are several reviews for many types of BH's, fixed and mechs. There are also lots of reviews on a variety of hunting and fishing items.
chris