I had an invitation test drive in one about a month or so back ( only because we have had 2 BM 3-series and a Cooper S from the local dealer ) and personally I think the 335i is a different character to an M3.
Whenever i've been out in an M3 they seem to do all their best work at the top end of the revs and they're a "harder" character than the normal 3-series.
The 335i I drove had lots of low end poke and was fairly effortless to wind it up to big speed - however, it seemed fairly soft suspension wise to me.
I'm sure you'd give an M3 a hard time in a straight line and he'd be really having to work his engine/gearbox out of slower corners. Think the M-cars would show their worth in the bends though.
I know the US mags got faster times than Autocar for the 335i though....but they always seem to so I'm not sure if they test the same.

If you're interested, here are the Autocar test times with real timing gear

335i
0-100 12.8
ss 1/4 14.0 @ 104
sskm 25.3 @133
30-70 4.9
1546kg

E36 M3 Evo 6-sp man
0-100 12.2
ss 1/4 13.8 @ 107
sskm 24.3 @137
30-70 4.4
1471kg


E36 M3 Evo SMG
0-100 12.9
ss 1/4 13.9 @ 104
sskm 24.5@136
30-70 5.2
1510kg

E46 M3
0-100 11.5
ss 1/4 13.4 @ 107
sskm 23.7@139
30-70 4.1
1577kg

E46 M3 CSL
0-100 10.9
ss 1/4 13.2 @ 110
sskm 23.1@140
30-70 4.0
1385kg

With a good suspension kit, maybe an aftermarket LSD & with 30 or 40 extra bhp, I think they'll make a fun car in 5 or 6 years time for not too much cash