Nobody runs 3:55 gears with the v6 ?
I may have read your question wrong. I find the 3.55 gears to work pretty well if not heavy trailering.. I have only trailered once. 5x10 covered uhaul loaded. 1000 mile trip thru KY, Ark, and TX. Had no problems with KY hills. Kept in tow/haul thru the steeper ones. Only gas mileage suffered as expected.
My uneducated guess:
I would think that 3.21 would hurt acceration and possibly cause more downshift on freeways to maintain speed.
The 3.92 would probably be a thrill if you want quicker acceleration or want to pull a trailer. It just means higher rpm's at cruise and lower mpg (?) .
I haven't run across any posts on codes from change-up. Seems like it would affect speedo . Maybe someone else knows what else it may affect.