So as an adventure person, I know it's sketchy buying used gear, especially stuff you will be falling on. So it is with my word as a lover of climbing and mountaineering that I declare to you: These harnesses have been used lovingly, mindfully, and with due diligence. That being said, harnesses these days are almost indestructible provided they have been properly cared for.
-- Both harnesses fit me (31" waist) and can go bigger. Neither can go much smaller than 31" however.
-- They are both size M.
-- Edelrid harness is a bit older, let's say $30 for that one. Non-adjustable legs.
-- Black Diamond harness is newer, more stylish and shiny. $50. Adjustable leg straps.
-- Both always used and stored properly, no intense water or UV exposure, no sharp edge encounters
-- Generally used just for single pitch sport climbing
Check out the link for the Black Diamond harness pricing, specs, and reviews.
Call, text, or email me (Adrian) to arrange a visit to check out the gear. I am open to selling all this adventure gear in bigger chunks (see my other ads).