I had Venice 3000 stepping BB and it couldn't pass 2.7G no matter what I tried. Upped voltage to 1,7 but it didn't help anyway.
Right now I'm watching some SD 3700+:
E4 KACAE 0606EPBW
E6 LCBBE 0640CPMW
E6 LCBIE 0625FPMW (this one runs 2,65 @1,3v stable)
E4 KAB1E 0631APMW (this one does 2970 @1,48 on Epox 9NPA, so maybe DFI will clock it better)
and one 4000+:
E6 LCB9E 0641CPMW

Right now I could test them only under water, but is any of those worth playing with?