After a 5 year hiatus, looking to get back into an E53

[DiscoStu]

I'm a former E53 X5 owner (2002 3.0) that might be looking to get back into another one. I'm curious to know though how well these cars have aged. I remember our old X5 seemed to have something break every week. It was usually something small (broken door handle, AC buttons falling off, cooling system, inactive airbag suspension, etc.), but nevertheless I seemed to constantly be working on it. Looking back, I never realized how much I missed hating that car. There was a certain level of pride and satisfaction in fixing it.

My question is, and setting the "small" stuff aside, are there any major issues that have crept up with the E53 now that they're around 15 years old? I would be looking for a facelifted model, most likely a 2006 somewhere in the ballpark of 100-110k miles. I will also only be considering the M54 3.0 engine. I did some reading last night and it seems as though the automatic transmissions are prone to failure? This wasn't something I've ever dealt with on my older X5, but it seems to be the "norm" now. Can anyone shed some light as to whether the E53 3.0 has widespread transmission issues? Is it inherently flawed, such as the E46 rear subframe, or are cases isolated?

The car would be for my wife, who currently drives a very reliable, yet incredibly boring, Toyota Highlander. She's hinted at getting back into an X5 and I personally love the idea. We also have two young children, so reliability is important. The reason we are targeting the E53 is better reliably and past experience. I will without a doubt get a PPI on which ever car I chose. I also have plenty of experience working on BMWs of this generation, in particular the M52/M54 engine. I owned an E46 328Ci for 10 years and currently own an E46 330Xi. I plan to do all maintenance and work myself.

So, good idea or bad idea?