Seems like things might get a little sloppy with the one large attachment hole.
Bingo. That large attachment hole is really awkward with eye-to-eye cords, at least w/ spliced eyes on 8mm OP. The hole "eats" half the eye, and the whole thing ends up binding in weird ways - at least in my few hours experience today.
I picked one up for a few reasons...
1) I'm a rec climber who climbs on RADS most of the time, and have beat the holy snot out of the Petzl oscillante on my hand ascender. It still works fine, but has loosened up quite a bit and I'm sure its days are numbered. The Tethys seemed like a nice step up from the cheaper "rescue" pulleys (It is!).
2) The pro version has ball bearings and published efficiency ratings, which isn't too common at this price.
3) Was hoping that it might work as an entry-level Hitch Climber-ish stand-in, with that double carabiner attachment... maybe? Nope!
I can't imagine anyone getting an eye-to-eye working well with two attachments. Even with smaller aluminum ovals, it bound up solid as forces shifted around. Even for simple lanyard adjustment with a single attachment, I think the dirt-cheap Oscillante works better.
It's a really nice high quality pulley - CAMP advertises it as a Prusik minding pulley, but they gotta mean it in a very different progress-capture prusik on a hauling system kindof way.