Good points Anerbe, and Others -

It's quite likely, that whether the 6000 lbs limitation came from the test track, engine/frame/transmission & torque converter engineers, the legal office, or some other entity at BMW, . . . we'll never know. No one wants to divulge their vehicle's weak link.

I can only imagine that 6000 lbs puts a "getting close" to limit strain on the hitch, frame, suspension, and transmission. Getting a V8 under the hood will only enable me to INCREASE that strain, and I don't want to do that. I don't want to be tempted to do that! So, just another reason to go with the simpler M54 with enough power, but not more than I need . . . UNLESS some members with BMW V8 experience want to convince me that the V8s are as easy, if not easier than the straight 6 to maintain.

I agree that stopping is a major concern. The X5 stopped this load during aggressive decel on par if not better than the Suburban. We're pretty committed to Florida, the only hills we'll see are the launch ramp and the exit ramp!

Love the sharing . . . Good Stuff!!