i know im late but I owned an SMG E46 M3
I had the best time of my life but I wasnt experienced in 6 speed as much (so what you really don't know abou tdoesnt bother you)
but i feel that the E92 M3 (with more experience in manual) is probably going to be "funner" than DSG.. even though DSG may befaster
What bothered me with SMG also is that every year the SMG "got better" and you can easily screw up the tranny and lose the car for1 year....
the 1800 l.c. block (european cars are chill because they are 3000)
and i asked a lot of people on M3forum.net and we talked about the joy of SMG and they all said that 95% of the time (for me 99%) they drive the smg shifting program, it is annoying to drive Auto on an M3....
so basically the difference within 6speed and DSG (without time factor which will be small) is that you are pushing the clutch on 6 speed and you can choose what gear you go into in the canyons for a nice turn etc.
I loved my SMG M3 but now I am going to give my 6speed a chance...
"if i dnt like it I will trade it in for DSG later"