personally i'm a supporter of giving all cruiser +2 turnrate up until a max of 10.
but in your case the solution is simpler: get the chevron separation console from the command oddy. RCS consoles are useless on cruiser, it is not worth putting on one if your base turnrate is below 9 or 10.
but why do people ask for better turn rates? using beams is 180-360 coverage, mines in the back, maybe a torp in the front?
The only reason i can thing of is 90degree sci abilities, and even then its limited?
well you are absolutely right, a cruiser with 6 degrees can do nothing really better than one with 8.
The only thing that would be improved is the handling of the ship to a point where it is not totally annoying to a point where you throw it into a corner and never look at it a second time.
it is simply a conveniance to be able to turn your ship around and engage again in less than 30 seconds.
Klingon cruisers have it, and even if you don't run them with dual cannons you start to appreciate the higher turnrate, just for the sake of a quicker response to your input.
there is hardly a tactical or dps gain involved in a slight increase of turnrate...it just handles better.
Being unable to control when or where you join a fight, being unable to avoid immobile objects, being able to shift fire to/away from shield facings easily, being able to get into/out of range of friendly/enemy targets (and probably plenty more examples that aren't sitting at the front of my brain at the moment) all contribute to how effective a ship can be in a combat situation.
I believe you can do three things to help your turn rates and I have used this as I fly mainly cruisers (liking them and being an Engi and all).
1. RCS Console at green or higher quality will always be of a boost no matter how little it gives. I think it is possible to stack these.
2. Impulse Power Skill will increase your turn rate as well.
3. <Insert type> Impulse Engines w/ [TURN] boosts. I prefer Combat Impulse engines as I rarely run my engines over 50 power (and when I do it is the balanced setting) as they are more efficient at lower energy levels. You could get away with the Aegis set too from what I've read up on it.