I went with a different Petzl saddle, the Avao sit-fast.
http://www.treestuff.com/store/catalog.asp?category_id=131&item=2177#detail
I got it with the optional (and detachable) top chest harness which can accept a Petzl Croll when desired versus the Top Croll Chest harness which has the Croll permanently sewn in.
http://www.treestuff.com/store/catalog.asp?category_id=131&item=2312
http://www.treestuff.com/store/catalog.asp?category_id=131&item=3431
I also have the Petzl Podium bosun seat for additional comfort during extended suspension periods.
http://www.petzl.com/en/Professional/Harnesses/PODIUM
I found I only use the chest harness when I'm working from a ladder. The chest harness does a good job of keeping my saw and other gear from pulling the saddle down while standing. Otherwise, the saddle alone holds the weight well when I'm suspended by a rope. I have climbed SRT both with and without the top chest harness, depending which SRT climbing system I'm using at the time. I always use the chest harness when using a Croll.
This is my second harness, and my first was a Buckingham tower harness. The Buckingham was great while I was a beginner ... was sturdy and provided a lot of confidence ... but it wasn't too long before its weight got a bit tiresome. The Avao is a very lightweight saddle, but is proving to be worthwhile to me. BTW, tree work is only a side job/hobby ffor me, so I'm not in the saddle multiple days at a time.