Austin, Have you had your car dyno tuned, or has it just been you messing around with the SDS (oh man I hope you actually have SDS, I cant remember for sure) Ive found with mine, having been screwing around with the SDS myself, its driveable, but not as good as I know it can be. I havent had any warm up problems or driveability problems with the SDS.
Its funny that you compare driveability to a 325i. We have one here and I cant stand the power delivery on it. I find it hard to drive in normal traffic as it makes no torque. it revs out nicely but thats only fun when no one is around.
I guess my vote would be to get your car dyno tuned. If it already has been.... then I guess you should do an RB swap