Hi, I am glad you like what I have here. Long story short: I updated the mod. in 1.0.2, you can control the firing pattern (arc or circle) and the firing arc degree. Go wild :)
Long answer:
I wasn't very sure about how to make these turrets distinctive. I definitely wanted to have a pros/cons situation where these rocket turrets are not the ultimate solution to all biter problems. I also wanted to avoid a tier system where the next upgrade is definitely better in every respect than the previous.
So the idea was:
1) shooting in arcs to be distinctive (since all other turret shoot in circle)
2) as maximum range increase, minimum range increase as well, so the turrets are less and less effective in short quarters.
3) increasing max range covers a lot of area. I opted for smaller degree for arcing as max range increase to let the turrets have some personality.