I wouldn't worry about MC15 or Prime if it weren't for the possibility that a future operating system change will make my MC13 unusable. I'd be glad to keep using MC13 (or MC11) and not spend anything on upgrades. I can live with all of the MC13 quirks.
I'm torn between paying $350 a year for a few years during the development of a MC15 replacement or getting nailed for $3500 when Prime V3 is released. Ahhh - the capitalist system at work!
Interestingly, we just started our ethical decision making training this week, and short-term vs. long-term came up as one of the canonical decision-making conflicts... ;-)
According to the PTC webstore, an electronic download for an upgrade from v14 is $85, which might be a reasonably cheap date:
So I installed the 30 day Prime trial, and went to convert some of my M15 files. It said I did not have M15 installed. Cripes - what next? There is no help on the PTC web site.