I'd be more worried about the lights and OBD inspections etc. w/ the LS swap. But being a GM guy (had a cam'd, sprayed LS7 C6Z06), I must admit that there's no comparison between the Hemi and LSengines. Once you bring the aftermarket into play, LS' are tough to beat period.
Would love to have an LS3 in my 2010 Unlimited Rubi
2010 Unlimited Rubi: 6 Speed, Nav, RK X Factor, Raceline Beadlocks, 37's, PSC Crushers, BFH, EvapSkid, etc.