You've got to think that Bell has anticipated operator concern over the selection of a Turbomeca donk over one from Allison or Pratts. Given that the SLS will be going head-to-head with the R66, I wouldn't be surprised if Bell were to adopt a similar harmonized major service interval approach, i.e. with the airframe and engine both undergoing heavy checks at 3,000 hours.
Another possibility is that Bell will use some kind of Power-By-The-Hour or Guaranteed Availability maintenance plan, to minimize concerns over TM's support. (This would also allow Bell and TM to maximize 'authorized' (vs. third party) MRO revenue.)
From a technical perspective, the Arrius 2 -- like the PW200 -- offers a number of advantages over the A250, in terms of TBO, SFC and design simplicity.
I/C