I bought my Benelli SBE2 with the intention of using 3.5" shells.
I've had it for more than 8 years and never shot a 3.5" shell once.
Loaned it to my friend for a Duck hunt and he used the 3.5's.
He said it was awesome out to 60 yards with the proper choke.
I have yet to find a REALLY good reason to punish myself with them.
3" has gotten it done for me up to this point.
Them damn snow geese