Two of us, with many thousands of miles, with Klickfix handlebar mounts and bags. Our handlebar bags are the catch-alls for everything we pick up during the day: food, souvenirs, bug spray, sun lotion, you name it. I'd guess we easily carried 15 lbs at times.

The cable (it wraps around and under the stem) is the key. I've removed the mount several times, and re-mounted it. The cable gets a little frayed where the bolts clamp it, so after a half dozen removals you might need to replace the cable. Most hardware stores sell steel cable (even stainless steel) that'd work. The Klickfix system is solid, much better than some other quick release mounts I've used or seen. I'm not familiar with the "frame adapter" you have, though.

-- Mark