Yep, I have the Transgo one fitted, upgrading the valve body. I also had major slippage so the clutches were upgraded with a full rebuild and high stall converter. It was the first one they had done like it, they had to laser cut the thinner steel plates to fit a few more clutch plates in. It cost $4000 all up around 2 years ago. Now you can probably get it done for half that.
It should handle a fair bit but I am aiming at 350-400awkw through it at perhaps 1400nm and no-one can tell me if it will let go. There aren't that many performance parts out there yet for the RE5 but they are coming.