In another thread, it was discussed that it is unfair, that weapons with a RoF under 1 in fact have a harder time aiming than the ones with 1+; this is especially odd with weapons like sniper rifles...
So, why not include into aiming, that it gives an additional +5 for each step the used weapons RoF is below 1 (not cumulative though) ?
1/2: +5, if aiming in the same turn
1/3: +10 if aiming in the same turn
This could help these weapons a little and would stand for the additional time you have during using that weapon to focus on your target.