An interesting discussion, I'd like to offer a couple of observations...
I'm seeing a lot of suggestions to make Fire Warriors much much better at assaults, given that in 40K they don't actually deal damage much different from tactical marines I'm curious as to why there are suggestions that involve putting them on par with Dire Avengers, supposely the all time masters of 'spray and pray' assaults.
Secondly, even from a fairly cursory look it seems that Firewarriors have a hard time finding a niche. As mobile firepower they don't seem all that hot, combinations of short range, enemy infantry nearly always getting cover from at least their own transports and a high likelyhood of needing a double to get to a decent position to fire from they're going to go down to 7's of largly ineffectual shooting pretty quickly. If you don't take make the approach when you shoot you're libable to be in assault before you get the chance to do much effective shooting at all so no winning there.
Its well and good to say that Fire Warriors are for counterattacking, but if their firepower isn't high enough to run and gun effectively and their firefight isn't good enough to assault then their counterattacks aren't going to be achieving a whole lot.
Before debating exactly which rule to make for the solution it would be best to aggree on the problem, I'm pretty sure the problem is that Fire Warriors don't have an identifable slot in the army that can't be done better by something else. Consider - Hammerheads shoot stuff better from further away, Crisis suits do mobile firepower better and can have a chip at vehicles while they're at it. (Of course I could be wrong, I'm not as highly experienced with the tau state of play as most you guys).
Perhaps the simple solution might just be some baby steps from the V5 list, upping them to a straight 4+ firefight with no icing on top. At point blank range a squad of firewarriors have a higher throw weight than a crisis suit, and they have a decent justifcation for it with 5 heads to look around keeping track of whats what instead of only a couple of battlesuits and faithful binky the wonderdrone...
IMHO they don't need to be great at firefights, just a bit less poor than everything else in the list.
