Parts availability is rarely an issue with OS. You can generally access a treasure trove of parts via the Tower Hobbies website. It's not quite as straightforward a search as one might like, but the parts are in fact there in many, if not most cases for OS motors going back 15 or more years. As an example, my OS.70 Surpass 1 motor (originally purchased in the late 80's) still has all parts available through Hobby Services.

AFAIC...OS has no rivals in the area of long term product support.

'Race