Based on my 15 minute test: Scrolling speed was good, with the caveat that obviously the longer the list, the more scrolling you need to do. As another previously mentioned, the BMW system doesn't go into "turbo" mode like the iPod does.
I found it very fast to load my lists of Artists, Albums, Playlists, etc. and I have about 10 GB in my iPod. Just a few seconds was all it took to suck the data in.
I am using iDrive. I can imagine it will be harder without, just because of not having the iDrive knob to scroll with. The new iDrive without the haptic feedback does make it easier. You can almost spin the controller...
I think it is bad luck to be superstitious