Pro's: The 55's would be a cushier ride, less pron to tire damage, "fatter-tire" look and less heat from the hard-core trail guys.
Cons: Well, a bit rougher ride, more pron to tire damage but not much, more of a slick, low-pro look then the 4x4 look.... still heat from the trail guys but not as much!!
Also, the 55's are an inch taller. I dont a rack on mine, and enclosed parking lots are a bit hair-raising at first... i can fit under a 7-2" so far, but that is about it. with the 55's, well, that is an inch closer, for me, to scrap so i dont know.
I guess if i was gonna do it, go for broke and really pas the margin with a 4-6" lift..