Really that's what the big deal is all about, my lvl 50 vengeful infinity fire 5600 dmg 10.4 rate of fire 3400+ fire dmg and 40% element chance sounds better then that. If I ever get 1 while playing i'll just hold on to it and dupe for ppl since alot of people seem to want it on gamefaqs.
The only difference is 10.4 Fire rate vs 9.0 Fire rate and 1 extra shot for every 4, which actually turns out to be 11.25 Fire rate.
Vengeful is consistent, while DVA can do more or less at any given time. Overall DVA does more in the long run, if you never miss a shot. But since infinity has a wide pattern, you can end up missing double shots at range.