I was originally looking at the SE for two reasons:
1) Stiffer ride (better performance)
2) Manual Mode (I've always driven manual transmissions, so I wanted this feature)
HOWEVER, I rented a MO for a weekend, and all they had was an SL. After drivng that around for a couple days, I have decided that I no longer want an SE, I want an SL!
The Ds and DL settings on the SL surprised me with how drastically it changes the performance, and I prefer it to the manual mode (another big surprise for me). The ride is quite a bit smoother, and you don't give up nearly as much cornering performance as I had first anticipated.
I highly recommend spending some time in both models. Not just a 10 minute test drive, I mean spend some good time with it. Sure, fly around some parking lots and do some hard accelleration and passing on the freeway. But then just sit back and relax and take a nice hour-long drive. That's what really sold my wife on the vehicle. We drove up the pass into the mountains. She read her book on the way there while I drove and we switched places for the way back. Nice, quiet, and smooth, even when I would step on the accelerator and swerve around the slow-pokes.
I found that I did NOT miss the slight performance gain of the SE, and having the smoother ride is a big benefit. Of course, you might feel differently, but you should definitely make sure of what you're getting.
~ Corin