I shoot trap with a mossberg 500 20 gauge and I shoot just as well as some of the guys with $5k+ shotguns.
If you seriously only shoot 500 rounds in the period of 3 or 4 months, just stick with the BPS. If you are set on getting a new O/U, get the used Franchi. Thats my vote.
There is no such thing as a stupid question, only stupid people.