All good points regarding how m54b30 lacks grunt in X5. But at least they aren't as much of a maintenance whore as their v8 counterparts.
I had an auto 3.0 x5 for a while and while it was never underpowered, it was definitely underwhelming.

Now that I have been daily driving my 525i touring 5 speed for a year , I can appreciate that little extra grunt you can wring out from the engine.