The 172 does what it was designed to do very well, simple as that. I've got a few hrs in them, from new ones, to some old abused beaters that should have been grounded. I got where I was going safely, and most of the time had fun enroute.
I was on the C-172/Porsche conversion project, back in the late 80's. What a pain. The project was a success in getting the STC, but it was heavier (which resulted in a lower payload), much more expensive, and more complicated, which means more maintenence (although the engine is very reliable). Sure the Porsche engine is great, but potential buyers looked at it and said, "with that price tag, I can get a nice C182, carry more and go 20 kts faster". So upon getting the STC, Porsche shelved the project.
I've been away from flying, or even hanging out regularly at the local aerodrome for years, so I don't know if Porsche has since decided to offer the C172 conversion again.
I was aware of the Mooney/Porsche conversion a few years back....but hadn't heard that it had been tried in the 172!
Learn something new every day here!!
Given that the older 172 is, with full fuel and very little baggage ( and the rear compartment is small anyway), really a three(3) person-max airplane, I wouldn't think that a heavier engine conversion would have been marketable.
'Course ... some people would buy it for that Porsche emblem. Haven't seen much on the Mooney since, either.
Ya' oughta get yourself current again. Flying has certainly helped my sanity. Up there I'm not thinking about that next world, or local, crises!!!
~GCR~