Acceleration could be fine, but I'd not like any of the other suggested things... I mean, heat is quite fine, slow speed is no biggie imo, still very possible to hit lights with them, you just have to predict where the little buggers are going.
Big + with acceleration: It will not sync perfectly with ANY weapon at ALL ranges. Also faster to hit slow targets at long range. I.e. it will effectively decouple them from all projectile weapons making it possible to balance them independently.
Big - with acceleration: Getting a "feel" for the weapon will be much harder at different ranges, so it may end up harder to lead properly to hit fast moving targets at medium to long range. Sure, you will have to estimate the range to the target also with a constant speed, but with acceleration the margin for error will be less for that range-estimate...
Edited by Duke Nedo, 16 October 2014 - 12:13 AM.