So I've had the tyres on for a few weeks now and they've worn in nicely.
Grip/Handling 
Superb! So far it's seems pretty unshakable. You have to really push it to get any slip and wheelspin under acceleration has been reduced too. I haven't had any moments yet so I can't comment on what it's like when the rears let go...
In the wet it's the same story, I'm not a fan of aquaplaning and these tyres definitely inspire confidence in the wet. Big thumbs up.
The only possible down side for some is that some of the initial turn in has been lost, to me it makes the car less twitchy, but some may feel that it's not as sharp. I don't mind though as it means you can be smoother with your steering inputs. I'm sure this is due to the increased width and the reduced side wall stiffness compared to the runflats.
Tramlining:
Gone. Fantastic.
Ride quality:
Much improved, make no mistake though, I have a R53
MCS and the ride is still pretty firm, changing to non runflats won't make any car that is designed to be sporty hugely different. But... it has made the car much better when you hit unavoidable pot holes. As I said earlier, it 'thumps' over bumps rather than 'crashing' through them.
Road noise: 
I haven't noticed a huge difference to be honest... I generally have the radio on or the supercharger turned up! If you pushed me I'd say it was a bit quieter, but I didn't think it was to noisy before.
Tyre wear: 
Don't know... don't really care... if I get 10-15k I'll be happy.
Sumary:
If you're thinking of changing tyres I would recommend these to anyone.
215-40-17 is a great replacement for the original 205-45-17 tyres, and is about as close as you can get to the original radius. I'm very impressed with TOYO Proxes T1R's, seem just as good so far as the Goodyear Eagle F1's I had on a previous car.
Just remember that if your in a Cooper S, you don't have a spare so sign up with a rescue service or get some tyre gunk and a compressor.
