Myself, I'm after a gun for every element, as it seems more effective than trying to create a gun that can use everything, like how the close combat weapons all just have one element. Anything that has rapid-fire shots for a non-element ammo type, like crag, cluster, etc., doesn't seem worth it, as those guns can't use anything else worthwhile. GK and I tried taking on Great Baggi with such a gun, and it took us 25 minutes to bring it down; after we ran out of crags and clusters, all we had to use were normal and pellet shots, neither of which are very strong.
This reminds me, I still need to meet up with you sometime, Ejamer.