I am VERY anxious for a Bristell LSA with the 915 IS!
One thing to consider is that reducing RPM for cruise caused an abnormally high number of Rotax engine failures on the early CTs. The aircraft was very slick and the props were pitched for performance. Pilots would often reduce RPM to fly slower. At first Rotax was very perplexed as to the cause of the problem. (Please correct me if I am mistaken or if there were extenuating factors.)
Rotax motors are are happiest cruising at high RPMs. They are not happy lugging at low RPM cruise with an aggressively pitched prop stressing the engine.
On the other hand, the 915 IS is strengthened considerably throughout for the higher HP, and actually runs on less compression. So maybe stresses would be better tolerated.
So if Bristell or any other LSAs pitch the prop on a 915 IS within LSA cruise parameters, the prop shouldn’t be too aggressive. Yet when you go to full-throttle climb there is plenty of HP!
I believe the early performance specs posted here from Dan Johnson were with an adjustable prop.
I’d be very happy with 2,000 ft/min climb and a solid 120 kts cruise.
Keep it LSA legal and let the turbo give you consistent 120 kts at altitude! 👍
I’d be interested to hear what Rotax says about running the 915 IS at lower RPMs in cruise.