Rustybarge
Guru
It was fairly expensive. There were 2 different sizes for two HP ranges. They only built them for a very short time, then stopped,...I don't know all the reasons why. (maybe legal concerns, see below).
I did hear of one installation on a big custom cat (French I believe) where the outdrive leg was hooked up directly to the engine without any intermediate shock absorption driveshafting, and of course it vibrated itself to dead. Then the builder/owner sought warranty on the item, when in reality it was an installation error.
As you said I think the concept has a lot of pluses over a Z-drive.
I've even drawn up a little idea for a duo-prop version...
Tennant Hull V ChainDrive
Thought about having the metal housings made up over in Thailand at one company I know of, then putting America bearings, seals, and drive chain(s) in them.
This UK company makes tip-up out of the water out z-drives for cats, but very limited in hp, which at least gets rid of water in the oil problem .
sonic_type_2_catamaran_drive