I agree with da Rock. I too have taught on both planes, and have played around with both pushing each to its limits just for fun and have done it in lots of wind performing vertical and backwards ground roll landings. There is nothing wrong with the NextStar as a trainer, and either will work just fine. I do prefer to start students off on the NextStar with the speed flaps and wing droops removed. Both planes have their quirks also but nothing that is a detriment to either design. It makes no difference to me what trainer a student shows up with - I'll work with him. Just because some flight instructor or flight school prefers one plane over another doesn't make one or the other better - different clubs/instructors do have their preference, but overall most trainers out there are all good flying trainers.

Putting an OS 91 (I'm assuming you are talking 4-stroke as a .61 2-stroke is pushing the limits of what the design will safely handle over time) and comparing it to the NextStar is not a true comparison. The Kadet Sr. is designed for a .40 2C, so if you want to compare the two, you need to power the NextStar the same. And for a comparison, the Kadet Sr. with a .61 on it is very close in performance to my Alpha 60 in most respects, and I have flown both on a .61.

Hogflyer