Ron, I've been around a few of the RMI drive units. Not saying they aren't great, as they are. I also agree in your assessment of the RMI vs. Diamond Drive. I think though, in reality, the biggest benefit I see and hear from people who own them is just that, they throw big HP at em and are happy to know they aren't going to lose a chain. Losing a chain means losing your brakes, and that usually means losing a sled.
The hyvo chain set-up has been found to be 98% efficient though, and honestly, if the RMI drive can find gains there, really, a 1% gain on a 150hp sled isn't really bread and butter stuff like the benefit of no chain to break is... If ya can get 1% on a 250HP sled, well 2.5HP isn't gonna get noticed either, that's all.
So, I'm not trying to say anything negative at all... Just pointing out what I see to be the biggest benefit of the RMI. (Safety with big HP sleds)
BTW, I owned a belt drive system and it was junked on day one.