Why would you keep the laser?
And why would you have fire on it?
Assuming you were putting a grenade launcher on it, it would be to fix
a) power level issues
b) terrain occlusion issues.
c) and to bring in more synergy with venom
Just giving it a whole other gun would send its power levels through the roof. It's bad now, but it's still usable. A grenade launcher on top of a laser would put it waaay over the top.
Leveler is in a similar boat to redback in power level, and this grenade launcher has similer dps, and greater AoE to a leveler. You're pretty much doubling it's power. So (a) isn't being served by this change.
If you're addressing terrain issues, then the laser needs to actually go... So (b) isn't really served by keeping laser.
If you're addressing synergy w/ venom, then again, the laser needs to go. So (c) isn't really served by keeping laser.
I'm actually for changing redback. It doesn't seem to fit, and it's a unit I never feel good making. But going ahead and making it two riots in one body... that would make it feel like some pre-abortion mini strider.
Also flames this way are a bad idea. That's kind of a third weapon, except it has terrible synergy with the fac that has a tendency to glob around and hate AoE. Fleas would be dead around it, venoms would sit in it while firing etc.