I also like my M62tub44
It makes really nice useable power. And that WOT V8 sound is music to my ears.
I had my big U-guide fail at 105k miles. I invested in the schwaben timing tool set and did the work myself. I also put on a new oil pick up tube because there were so many pieces of plastic in the pick up tube strainer that I didn't want to chance anything slowing the flow of oil to the pump. Guide failure is not the end all of the motor. Doing the work wasn't that bad. The job was big but not as big as the ZF5HP24 rebuild. I'd still buy the M62tub44 again.
Since the guides are "plastic" I think that heat and age play a bigger factor on life of the guides rather than mileage. Slack chain will wreak havoc on the guides too.