This is still all about the fact that the Hellfires used to have a slightly unfair advantage in average skill to low skill lobbies... people who couldn't dodge them complained... and Adhesive replied with, "We are going to work on the Hellfires. We're going to start by giving an excessive nerf to their speed and tracking, see what results that brings and then slowly build them back up until we feel we've hit the sweet spot.
And so they performed their excessive nerf to travel speed and tracking turn rate... and then never made another single update to the game again.
So, in my opinion, that's the first thing that needs to happen: someone at ReLoaded needs to start slowly increasing their travel speed and tracking until that is in a good place.
Then I think they need to work on the warning system other players get when they have been fired - so that it is easier to tell the general direction they're coming from and how close they are. Thus making them something that most players can learn to dodge with good timing. They aren't hard to dodge at all right now because they barely turn to track at all and fly slow. The people who have spent so much time on the game and have exception reflexes and situational awareness can dodge them by instinct... but a better warning system would make it possible for more players to have a reasonable chance of dodging Hellfire rockets that are faster and turn more quickly. Harder but also easier - better for everyone.
Then, there's the original point of this topic, improving dumb-fire. It's my opinion, still, that the dumb-fire only needs slight adjustments to get it to a good balance that makes it useful, but does not make the Rocketeer OP by making it too versatile at all ranges. I think if they're dumb-fired, they should move just a little faster, have just a little better grouping and have just a bit more splash damange. Also, their damage should be absolutely consistent with being locked on - meaning each individual rocket should do the same amount of damage just because it hits the target - locked on or dumb. It's still the same rocket and carries the same payload either way. So, if 4 of my rockets hit a target I've locked on to, they should take away the same amount of health as if 4 of my dumb-fired rockets hit the same target. Same for splash damage.