Solars do fire damage, and two pyro perks in, Though with a solar in each hand, and the risk of losing lots of solars in their inventory would make it like wearing HPA, and using two Bozars.
Though since Solars are found in caves, they are much more common, yeah I can see that as unbalanced until Solars are rare tier 4 items like implants.
I'd still support that idea though, make the solar something rare.