I've had experience with both auto and non-auto hubs (just not on the same rig).
Brand new pickup (had about 18000 miles on it) and headed home up the hill. Pulled the lever to engage 4X4 and the light came on. . . all is well. . . sort of.
Started the climb and then there was a grind and a bang. Hubs fine, tranny fine, 4WD still works- but I don't ever want to hear that bang again. Manual says that sometimes you will hear a noise- this is normal. . . . uh. . yeah. . . right.
Sidekick has manual hubs. I like the fact then when hubs are in and I'm cruising that-- as soon as I pull the lever I'm in 4WD. . . no waiting. . . wondering. . . . and NO BANG!
I've never seen an auto-hub rig that didn't say that the grinding, chattering, clunking bang is normal, but I can say if the 4WD goes out in the kick I'm pretty sure that there will be some warning (hub chatter/cv-joint clacking/etc). I've heard from people that have the same pickup that I do that one day it works and the next it don't. . . And when they quit there is no quick-get-me-home fix. When it's done it done until you change out your defective part.
Manuals are better IMHO even if the auto is more convenient. I might even change the pickup to a manual setup if it's affordable. I might even save some gas doing it. . .
If it isn't broke, why fix it?
just my two cents.