Thanks for your message! I'll get my new mechanic to have a look. I've pretty much given up on the dealer - especially in light of the fact that they've dropped the Rodeo line in Canada much to my disappointment.
This has been a great vehicle all long and I've owned it since new.
To answer your question, it's a 4x4 and the noticable humming started two years ago at about the 60,000Mi/100,000KM mark. I say noticable because it has increased so gradually over such a long time but might have started before that. I was beginning to think that maybe the differential gears had worn a bit and therefore were spaced incorrectly and that this was causing a meshing "whine". But your suggestion sounds more likely because it sounds SO much like a bad bearing to me.
Is the center carrier bearing the one on the front end of the differential case where the driveshaft connects?