For 6 years I've never used any scaling what so ever on my roll axis. I'm going to give it a whirl.
Good idea, bad idea?
As Rolex has already suggested, put your sliders all the way to the top for the best response to your roll commands.
In combat, the difference between winning and losing can be a tiny fraction of a second. You don't want that difference to be determined by your controls, particularly in roll. However, depending on the aircraft you fly there are various other techniques that I have employed with success, but it is very dependant on aircraft type. For example, with aircraft that already have good roll acceleration and a high roll rate combined with the tendency to snap roll close to the edge, I find that having all the sliders at the top, but using a small amount of roll damping gives more precise roll control, and softens the stall slightly. You do lose a little in your OODA cycle, but it can be worth it... It has to come down to personal preference.
For aircraft that have poor roll response, slow roll acceleration and roll rate, such as the P-38s for example, I use modified calibration technique, that reduces the distance I have to move the stick to achieve full roll commands. I only do this when I know I will be flying a certain aircraft for some time, and that of course is the best way to learn an aircraft. What I do is this... During the stick calibration procedure, when requested to move the stick fully to the left/right I limit the stick movement to the left and right by inserting the end of a pencil into the mechanism, which reduces lateral movement by about 1/4". That way I probably shave a couple of tenths of a second off the time it takes to go from full left to full right roll, as might be required in a scissors maneuver. It really does make the aircraft feel more responsive. It also works nicely with other aircraft, except those that allready roll well, like the Spit16 and Fw190 both of which can get away from you. You will need to experiment in order to optimize it for your own equipment and control technique, but it is well worth spending the time. It can take a while to get used to it, but anything that gives you even the smallest fraction of a second advantage, will at some point translate directly to kills.
Hope that helps.
Badboy