Not really ....
The 3" chamber will allow you to shoot "magnum" loads - but the only time you'd need to do that is for waterfowl ....and not to many shooters will take an old Browning out waterfowling.
The gun has a "field stock" on it / angled comb, etc ...so shooters will use it for upland birds grouse, phesant, quail, etc ...and whether its chambered for 2 3/4" or 3" isn't going to matter to anyone. But in general, I think all of their guns with "field stocks" are commonly chambered in 3" - same as the "field stock" models of the Citori today - like the Citori Lightning series.
Is the gun worth the money / and your time - yes, probably. Is it worth more than the equivalent Citori Lightning series - maybe, maybe not. My buddy OneOunce likes the Belgium made Brownings a lot more than I do ...but in most areas the Superposed will net a few hundred dollars more than the equivalent Citori. But the value is the feel and balance of the "Superposed" vs the Citori ---not whether it has 2 3/4" or 3" chambers.
Your market for a superposed or a Citori ....is not really the "synthetic stock crowd" ...where, when it comes to "hunting guns" - they all seem to think they have to have a 12ga chambered in 3 1/2" ... when a 3" chambered gun will do most anything they want to do. But the Superposed - you're looking at - isn't really a sought after Skeet or Trap gun either. Today the trend on "target guns" - is parallel adjustable combs and 30" barrels for a general purpose gun / and 32" for a Trap gun ....
But if you buy it / clean it up a little ...I doubt you'll have much trouble getting your money out of it ...selling it primarily as an Upland hunting gun. But some guys will shoot it for Skeet, Sporting Clays as well...