Mine runs the latter, installed by the previous owner, with no problems so far. Less prone to kerbing and all that, and still narrow enough for a bit of fun. Unlike the 275's on my previous S-Type R, which were more "gripgripgripgripgripgripSLIIIIIDE", if you get my, er, drift....
Bridgestone SO2 & SO3's used & OK, Pirelli Nero Zero or Dunlop SportMAXX used on other cars & will be tried next, currently on Falkens which are very good, lots recc Goodyear F1's, very impressed with a set of 2 Nankang NS2 that I have up front & £100 each!