I've had a set of 205/50-16 M500s on my S since August, and have been very impressed. Mine are mounted on 7.5" Kosei K1-Rs, and were preceded by multiple sets of Falken Azenis (215/45-16).

I bought the M500s when the 215 model Azenis became scarce and decided to use them just for street tires. At the same time I bought a set of 15" Koseis and Avon Tech Rs for autocrossing. Previously, the Azenis served both purposes.

The Avons are much quieter than the Azenis (not hard to do). Grip is surprisingly close to the Azenis, though not quite at the same level. I did run one event using the street Azenis as it was cold (45-50 degrees and overcast) and the forecast was for rain - not good R compound conditions so I left them at home. Tire pressures ended up slightly differently than my Azenis setting, but the Avons really behaved themselves very well. As noted before, grip is high. Breakaway characteristics were easy to deal with, and the tires recovered pretty quickly.

I suspect that I would have been a several tenths quicker on fresh Azenis, but the fresh Avons were equal to the Azenis dry grip when they are nearing the end of their life. The closest comparible tire in behavior that I've experienced are probably Bridgestone Pole Position 3s, but the Avons are far cheaper. These are clearly summer performance tires but are far more civilized than the Azenis, and I think they would be a great choice for street use, or even autocrossing if you aren't commited to getting every last tenth.

Scott
90SM