I posted somewhere back in this thread of my Gitzo 1541T fully extended holding my gear, I recently acquired a monopod to complement it so here's the set (collapsed cause I was feeling lazy.)
Gitzo 1541T tripod with Markins Q3T head and Gitzo GM2561T monopod with the Joby Ballhead X for QR and tilt functions. The Joby ballhead is a screw clamp that is fully Arca Swiss compatible, weighs about 9 oz, and it works very nicely with my Kirk plates. The monopod/ballhead combo is just over 1lb, which makes it nice and light for carrying around, and in my initial testing it holds up well even under my 60D with 100-400mm lens attached. Note that I don't have to extend the bottom leg section much or at all because I'm not very tall, and that really helps with the stability.
Supporting Pair by Meghan A, on Flickr