Thompson Unicender

[Buford]

An arborist caving buddy has introduced me to the idea of possibly using a Thompson Unicender while caving:
http://www.wesspur.com/ascenders/unicender.html

It takes the place of a descender and one ascender. It can be used on SRT or DRT (double-rope technique). It "converts" a static pit rope into a dynamic rope, obviously quite valuable during on-rope falls. Too good to be true? Well, it does cost $300. Have any cavers here ever tried out one? The video in the link above wowed me, but I'd appreciate any opinions from cavers here that have actually tried one.

My buddy is going to buy one for his arborist work, so I think I'll get the opportunity to check it out in a tree and maybe a cave.

Thanks!