Thanks! I pretty much only care about what mulches better, and what deck is better. If they are mostly the same but one mulches better than the other I will probably want that one. I only care about mulching because I don't know if I will ever be side discharging. Because I mulch 98% if the time.The Velocity deck has a much larger discharge outlet and some minor differences in the removable/adjustable baffle across the front. Scag machines with Velocity decks have the adjustment on the left front support chain.
I sometimes mulch with my 48" Velocity deck using G3 blades and a blocking plate. I also use the G3 blades all the time, mulching, side discharge or collection system installed.
I tried G6 mulching blades, but the airflow created by them causes extreme blowout, G3s not near as much.
What machine are you looking at?
Just a few Scag walkbehinds still have the Advantage deck and older ZTRs, everything else has the Velocity decks. Scag does make a mulching system for Velocity decks, pricey and their blades must be used.