Couple of answers:
1. After removing the Sprint Booster, my Active Steering has returned to normal. I have not read of ANYONE else that has experienced this particular problem (and I did a lot research before purchase).
2. No, it's not "snake oil". Read my earlier post for what it claims to do. It does what it claims to do.
3. No, it's nothing like DS mode.

After having installed and removed it, I can see that it can be a pretty quick operation to do that. I do NOT recommend the Sprint Booster (at least for the E70) though. I have listed most of the reasons in my earlier post. Some more reasons are:
6. It would be a real hassle to remove it and re-install every time you take the car in for service under warranty.
7. You would have to hide the switch, that switches between the 3 modes, before anyone else not familiar with the SB drives your car -- the SB could be dangerous to anyone unfamiliar with the car. This could be auto shops, valet services, etc.

If you have an older BMW, I suggest looking at a different option to increase the torque/HP instead. Having said that, I could see that a SB might help a small car like the 328i to be more responsive. I drove a new 328i loaner recently and I could not believe how sluggish it was.