changing the flamer projectiles shape and physics could be nice, I think it should be long (like a stryer) and the route should remember a Deagle projectile (curved), but weaker. Maybe the very few first projectiles could be slower, that would give the impression of a flamer.
There isn't any popular (sub)game mode that is based on flamer projectiles, so I guess is ok
The jetpack thing is too much for soldat, it would loose its simplicity.