i thought porting could reduce recoil slightly as it gives the gases other directions to escape, meaning the force vector is not 100% back into your shoulder. i don't know if it's relevant with a choke tube though, as the gas would be going every which way in like another 1/4" outside of the barrel anyway.
the gun i hunt turkey with has a ported barrel but i still use a ported briley choke with it. for one, it's easier to take in and out. no wrenches. secondly, it looks cool. and finally, it gives the barrel a little more length. very little more length. but when you're trying to take a 30-yard shot on a head a good bit smaller than a baseball, i kind of feel like every little bit helps. even though by the time you hit the porting the barrel really isn't directing much of the shot any more anyway, in my head it seems like it might offer some help. probably not, since most turkey guns have super short barrels anyway, but i afford myself a indulgences in irrational thoughts every now and again.