I know you mentioned NYC however if you are willing to make a hike to CT I'd be willing to accomodate your desire to experience an aftermarket setup.
Just a side note, I had also the same debate between coilovers and just springs and for now this does the trick untill my current setup falls apart and needs to be replaced.
I do not run anything crazy but the typical H&R Sport Springs with Sport Package Struts. I am also not an XI owner, but a RWD owner. These are mild differences but I'm sure they will affect the experience and might want to get your experience closer to your car make and configuration.
I am pleased with my H&R Sport Springs as it does bring an asthetic look to the car and also slightly enhances the driving experience for me.
I would not mind even letting you drive the car to get the full experience (as long as you know standard). Its truely going to be the only way to get the feel of how the car maneuvers. I have a lot of faith in BMW drivers but keep in mind... if you do crash it... i will kill you, lol.
I need to run errands in the Stamford, CT area between this weekend and/or next. Therefore I can meet you there so you can take a 10-15 min spin with me as a passanger.
Picture of the car below:. The front lip is off of the car for repairs since the H&R Sport springs has caused some damage to it... still worth it because it looks like sex.
PM me if your interested and we can exchange numbers.