Nope,it's not necessary. It sounds like a nice idea and setup, but it's not necessary.
Just for comparison,tho, my HD 870 has no choke, a lengthened forcing cone on a 18" bbl and my old duty load cuts 20-24" patterns at 25 yards. As for reducing recoil, with the sidesaddle and extended mag, the piece weighs 9 lbs plus and recoil's not a problem.
With this piece, anyone with some proficiency could traverse fire 5 targets at 15 yards in 5 seconds with good hits. I used to able to do it in 4, maybe I still could.
Everything I've heard about Vang is good, but IMO, the money(unless you're loaded with it) would be better spent on ammo and range time.