In short, yes I think its worth it. If you can find a decent one for a good price and do the maintenance yourself, it's not a bad choice. The M54 is a reliable engine, a bit lethargic in the X5 but still enough to be satisfying.

The cooling system is the most important in my opinion.
Radiator, water pump, housing if plastic, thermostat, expansion tank, hoses, fan clutch, etc.

Coil replacement isnt necessary in my opinion, just carry a spare. You may want a code reader to reset transfer case adaptation values after the fluid change. Some may argue you don't need it but I disagree. I used my Foxwell NT520. The only other thing you may want to consider is a trans filter change, and be prepared for some suspension component replacements.

For what it's worth, my second vehicle choice was a 2001-2007 Toyota Sequoia or an LX470. I also have an Avalanche and would consider replacing the X5 with another one. Those 2 vehicles are in similar price ranges and fit my needs in a daily driver.

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2000 e39 M5 Titanium on Black
2006 e53 M54 Titanium on Black
2007 e83 Black on Black Sport pkg
2004 Avalanche 2500 lifted 4.88 gears
1994 jacked up Jeep
1987 GMC lifted short bed on tons