I did this very thing for my SuperNova tactical (made sense to me). Its funny though, my Mossberg came "from the factory" with a nice forend rattle as well. But, sure enough, many peeps merely called it a feature of sorts and really had nothing negative to say about it (dont get me wrong though, I love Mossbergs...particularly the 590/590A1). Also, many Remingtons I have tried rattled as well. But, for some reason the Benelli shotguns have always been criticized for the same damn thing. Stupid.
Either way, yes...I agree. Tightening/loosening those two hex screws make a difference, one way or the other. Personally, I applaud Benelli for having thought of adding those screws in the first place. Just goes to show that Benelli does indeed pay close attention to detail.
The only thing I have against these Novas/SuperNovas is their capacity (speaking of the "special purpose" models) and the lack of a front bead sight only configuration.
If they could up the standard tube capacity to 6 and allow for front bead sights as an option, well...I probably would not own anything else as they are, IMHO, one of the highest quality pump shotguns you can buy for under $500 brand new.