In reply to aldo56:
I read that recently but I think actually 4 loop harnesses that have only a little tab at the back (which Edelrid amongst other seem to do) make it more likely people will try and wedge a krab in there to hold something than with five loop harnesses, even if that back loop is a very minimalist one (eg:
http://www.ukclimbing.com/gear/review.php?id=5228 ). Those tabs on the Edelrid ones are small and hold a krab tightly in just the place Andy worries about, but I'm not sure what else the tab is designed for? I've never got people hanging their chalk bags by a krab from the harness anyway, totally the wrong place for me and I want to be able to move it from side to side, so just use a belt or prussik loop for that.
I see Andy's worry of things ramming into your spine if you fall, although I'm not certain whether a fifth rack really increases that risk greatly. I did break a rib (or ribs?) (for a second time this summer!) when krabs holding cams on an over the shoulder sling I was using as bandolier jammed into my ribs as I was grunting over a small overhang. Having now broken ribs twice since May, I can really recommend NOT breaking ribs to everyone, and as a krab was the instrument the second time, I do sympathise with Andy's point - where your gear is held on your body in relation to your bones is worth considering, something I wouldn't really have thought about before.