Well, I dont plan on doing any mud crawling. Just descend the pit and back up. If I decide to go caving I will by a caving harness. Is it possible to use a rope walker system with the Tengu?
I don't know a lot about caving, didn't realize pit climbing was a separate discipline, thought that cavers used the pits to get to the caves. So it sounds like you'd be good with either tree harness in the pits.
Yep, you can do a ropewalker on the Tengu. The Croll can attach to the center delta, I'd recommend ordering the pear screwlink option instead of the stock delta screwlink to give you the room to put a Croll on and other hardware as needed. I attach a hitch (substitute for Croll) to an inverted HMS biner on the legstrap D for my primary ascender backup, I think you could use maybe a Petzl OK biner to attach a Croll to the legstrap D. The thing to do is call up New Tribe and tell them how you want to configure your SRT system and they can tell you what will or won't work best with the Tengu. They're based in the PNW and work with a lot of SRT climbers.
The Sequoia is designed for a Croll attachment so you'd be good to go if you went that route.
For the Tengu they'll do custom work and add an attachment point on the back for a Petzl Secur shoulder strap etc. if you want it.
I'm probably not helping you make a decision, you'll be happy with either harness. You'll spend considerably less on the Tengu even with custom attachments.
-moss