Megavore works even better for multi-projectile weapons like shotguns, mashers (that now can come also as ARs in addition to pistols) and (if they exist) anarchy smgs. Every projectile is an individual hit, so your chances that “Megavore” triggers is increased, which then results in a higher chance to proc “Leave No Trace” for refunding the whole shot. This can cause long chains of shots without losing ammo.
Here is a good example for this: https://www.youtube.com/watch?v=p_TxcR78WFU
But you can achieve that without “Megavore” when you aim for the crit zones. “Megavore” gets interesting for cases were you can not do “natural” crits. One good example is the Proving Grounds boss, as it is a skag it can only be critted when it opens its mouth.
As seen in this video, Zane can not crit the skag with his Torgue shotgun (both impact and explosions): https://www.youtube.com/watch?v=Vvo3r_aPdKE&t=560
But FL4K can do it thanks to “Megavore” and can even chain a lot of hits thanks to using a shotgun: https://www.youtube.com/watch?v=p_TxcR78WFU&t=500
With “Megavore” you have this crit chance progression
1 pellet = 20%
2 pellets = 36% (0.2 + 0.8*0.2)
3 pellets = 48,8%
4 pellets = 59,04%
5 pellets = 67,232%
So if you have a shotgun which shoots 5 pellets per shot and all hit you have a chance of 67% that at least one of the hits is a crit. Thats quite an improvement compared to the 20% base chance.
On the other hand “Two F4ng” is not very good on multi-projectile weapons. On single projectile weapons having an extra projectile at 25% chance translates to a 25% extra damage multiplier or 5% damage per skill point. But on multi-projectile weapons you lose a lot of the damage potential. For example shooting 6 pellets instead of 5 pellets with a shotgun (= 20% more projectiles) at a 25% chance only translates to 0,2*0,25 = 5% effective damage increase or 1% damage per skill point. It can still be good as it is still a multiplier and not an additive damage bonus and you can use it to go down in the tree, but its not as amazing as Zer0s “Tw0 Fang” or Mordecais “Gun Crazy” in the previous Borderland games (although “Two F4ng” doesn’t cosume extra ammo).