After much consideration, driving and internal conflict I ended up going for a Porsche Cayman S 987.1 with the 3.4 M97 engine. Yes this is one of the main ones that can get bore scraping so that is something to keep a close eye on, but so far so good.
Initially I was looking at E46 and E90/92 M3's, Audi S4's (3.0 supercharged), a Porsche 996 911 and the Cayman. The BMW's are great cars, the E46 is more practical with a bigger fuel tank, the E90 is faster and more expensive to run, but they are both heavy. The same goes for the S4, which can be remapped to 470 bhp quite easily but is not particularly involving. Chris Harris drives both an S4 and a Cayman on roads near me which also helped make my mind up.
So it boiled down to the Porsches. They drive quite differently but are very similar in terms of straight line power. The Cayman however is excellent at handling. The 996 911 has challenging and rewarding traits, which may be more rewarding potentially in the long term but the Cayman is spot on immediately. Steering feel, balance, poise and the controls all feel right and I prefer the way they drive. So that was that and I had to find the right one.
I ended up with a Basalt Black 2006 (MY2007) Cayman S with lots of spec. Some of it I didn't want, but it was the balance of everything and condition of the car that sold it to me. It has 997 Turbo 19" wheels so it's a good thing it has PASM, Sport Chrono, unfortunately it has BOSE too which isn't very good. It had also just recently been detailed and coated with GTechiq C1 ceramic coating so it should help it look spic and span for a while.
I had an inspection done which found no bore scoring and everything in very good condition generally. It does need a new aircon condenser but that was used to negotiate the price down somewhat.
I haven't had a chance to take any decent pictures of it yet, so I'll put up what I have.