Measurable,yes, "Feelable", probably not. We did a thread on porting recently, a search of the Archives should bring it up.
A shortened version....
For barnburner loads like the 3 1/2" Goose Howitzer ones, 1 7/8 oz turkey stuff, or the big slugs like that Brenneke 1 5/8 oz Mastodon Stomper, porting makes a difference one can feel, by most reports.
For any of the clay games, porting adds to the noise and blast factor, and the occasional piece of detritus flies out and makes life difficult for someone nearby. Some styles of porting are a stone cold %^&* to keep clean.
If you're recoil sensitive,fighting a flinch, or set on not getting one, AND HAVE DONE THE BASIC STUFF TO REDUCE THE KICK,then porting may have some advantages. Haveing the forcing cone done will do about the same for cutting kick, and aid the pattern. Backboring does too, but I've grave reservations about taking bbl metal away.
The basic stuff includes, good fit, good form, a load weighing less than 1/96 of the gun weight (the old Rule of 96), reducing load velocity and mass, etc.
FYI, my trap load is an oz of 8 1/2s at 1150 FPS.
I frequently run 25 straight, average is maybe 24/25. There's no big red S on my chest either.
I tried 7/8 oz, and hit most of them, but noted more chips and less explosions.
The Technoid, over on Shotgun Report, says one loses about an inch of usable pattern diameter when going from a 1 1/8 oz load to a 1 oz. The Archives there have lots of info on this.
In your shoes, I'd use that Browning(NIiice gun) with 1 oz loads, make sure it fits, and work on my form before kicking out shekels for expensive mods and addons.
HTH, and see you on the range...
