Re: What Reliability Improvements in 9A1 vs M97?
A couple things come to mind on the 9A1. Overall it's better suited to track use. Can't recall the details but it has more pickups and oil pumps than the M97. There are cases of oil starvation on track with the M97 but I've not heard of any instances with the 9A1. There is a video of a 9A1 on a articulated test stand. You might try a search for that. Also the M97 has reported cases of rod bolt stretch and some recommend limiting revs to preserve the bolts. The 9A1 bangs off the limiter without issue- at least mine have.
To the question of whether the cost delta is worth it, that's an individual assessment. For street use an M97 would likely be fine. For track, one could spend on a deep sump, baffles etc and still be money ahead, but overall the 9A1 seems more robust.
2008 911 Carrera S (sold)
2009 Cayman 2.9 (sold)
2012 Cayman R
2004 Boxster S