I think that smithrjd got it all right. If you're mainly an upland hunter, you want the Ithaca (we used to say "legs kill grouse, not shotguns" and an extra pound can sure tire those legs out over a long day fighting snow and brambles). If you're an upland hunter who sometimes hunts ducks, still get the Ithaca. If you're mainly a waterfowl and/or turkey hunter, get the Browning.
This pretty much sums it up but to put a finer point on it, if you're mainly an upland hunter get an older Ithaca with a receiver that will accept only 2-3/4" shells and with a fixed choke. As has been stated, no harm in using steel shot up to a modified choke so you're covered for non-toxic-only upland areas or ducks in flooded timber or close over decoys. The Ithacas with receivers that will accept 3" shells are heavier than necessary for 2-3/4" upland shells but not heavy enough (for me) for shooting 3" loads. If you're mainly a waterfowler who shoots a lot of 3" shells, get the Browning. I don't think I am particularly recoil-sensitive, but I don't care to shoot 3' shells in my Ithacas. The even heavier Brownings are better suited to such loads.
As to getting a new choke-tubed barrel for an Ithaca; yes, that is definitely an option if you are still concerned about the use of steel shot or just want a little more versatility. But be aware that choke tube barrels are heavier than their fixed choke counterparts; a fixed choke barrel is much livelier. The gun will not handle the same with the new barrels.
The safety location is also something to be considered, although it is of secondary importance to most people. I like the tang safety on double guns, but my safety thumb is sensitive to cold. The Browning safety is a steel slide recessed into a steel receiver. When it's cold, I can't feel the safety. No such issue with the Ithaca. This issue is probably more acute for me, as my safety thumb is somewhat numb all the time due to some nerve damage.
Good luck with whichever one you choose.