Sleeper - that's a great way to explain the difference and I apologize if you were offended by my comparison. The X5M has a lot of great features about it. I didn't test drive one long enough to experiment with the settings that you mentioned. Had I been able to, I might have noticed the difference.
But if you compare the two (X5M to the X5 5.0i with the M Performance Package) and you leave both in their default modes, the throttle responsiveness when both are compared in their default start-up positions are noticeably different. The M Performance Package on my X5 has the fun-to-drive feeling that I didn't notice with the X5M at the time and for the $25K or so difference in price, it wasn't worth the leap to spring for the new X5M but, I know I didn't get a lot of the other performance features that your M has on it but that's what makes the M such a special car, eh?
For the extra $25K, I can do a few mods at my leisure and enjoy the process of researching different options and learning more as I go but for now, I'm extremely happy with the equipment packages I was able to purchase on the 5.0i that I'm driving. When I hit the lottery this week, I might order an X5M. We'll see!