This is what I have HEARD, and I stress HEARD, about the gears:
TTS are harder than Robinson. They are treated? to have a harder surface than the Robinson. Thus they ALLEGEDLY are less prone to cancer. I have ALLEGEDLY heard of 5th gear failures with them.
The Robinson are chrome moly, with a Rockwell hardness of between 52-54. This is not hard enough to keep them from getting pitting. However, ALLEGEDLY there have never been any KNOWN failures of them. When I say failure, I mean a catastrophic blowup while under steam. Mine were trashed after one season. Severe pitting. And once it starts, it doesn't stop. Then again, I don't know anyone who is using 500+ hp on the top end with these gears, either.
In an attempt to have them survive this season, I had them micro polished, Microblued, and cryogenically treated by Mark at R & D.
Walt