I wouldnt bother with the 3.5 inch.I shoot geese n dont bother.@most you may get an extra 6grams of shot. As the bigger cartridges arnt actually anymore powerful you cant shoot at longer ranges so therefore a 3inch will be fine.
+ 3.5 tend to have problems cycling small low powered rounds so clay shooting is not always going to be an option.

However 3.5 inch look so cool so you know, I dont think You need it but its up2 you.

Tomy D