asking this general question primarily for a touring bike build.

Ive toured for about 25 years and do all my bike maintenance, regreasing hubs etc, repairs, but have only ridden on ball bearing bbs and square taper. With my square taper bikes Ive had very good experience. On my commuter, its UN-55 quality shimano bb lasted probably 12 years with probably 25000km on it, so I use that as a reference to excellent life, and I ride as soon as snow is gone and into December here in Montreal. A few years before I replaced it, a creak started, and I removed the bb, cleaned out the threads, put liberal amounts of grease on the threads, reinstalled and it stayed quiet for another few years.

with my project for a new touring bike, I see that there are reasonably priced 44/32/22 shimano deore 590 level cranks using hollowtech ll external bb's, but coming from my lack of experience with them, and conflicting experiences from other riders of how long they last, I'd like to get your experienced views on real life bearing life with them.

The lighter weight is nice, and I do understand how they are a lot easier to work on, but I could go either way.

I don't weigh much, 140lbs, so don't put out much torque, and my knees and legs prefer a faster cadence now at over 50 as when I was 25, so I imagine this helps with bb's just like it does with all drivetrain wear/life.
Are there big differences in ext bb life from one type of ext to another? Just as there is with varying qualities of square tapers? Like I mentioned, this Hollowtech ll is used on those trekking cranksets.

I've been hoping for a few years to do a much longer touring trip in Latin America, so I'm ok with the slightly heavier square taper if it really is more reliable and longer lasting. I do keep my drivetrain clean, although from inexperience, I don't know how much this plays into ext bb's lifespan of stuff getting in, and a trip in Latin America is going to be more gungy overall than my city riding here.

thanks

I'd appreciate your experience and insights