"....the other air through the engine backwards is limited to aTBOat 3500 and Hots at 1000."
I thought the base HSI period for a -114 was around 1,500 hours (or more?) and I think most Caravan engines would be on a TBO extention program? I have known -27s and -34s on condition to run 10,000 hours TBO.
The video clip proves only that 900 HP is 33% greater than 675 HP with corresponding increase in aircraft performance. There is also a fair chance that if one were to install a PT6A-67 (1,200 HP) in the Caravan it would probably outperform the Garrett equipped aircraft?