I use one of these cheap controllers deans put up, been on system about a year and really pleased with it!
I have it turned right up with 2 reels going off it, and about 1/2 for one reel, plenty of water coming out.
Dean we DO NOT have the water coming out slow lol, we are concerned about saving water yes only having 350 litres on board, but like you say if you have it on quicker you get the work done quicker.
Anyway, thumbs up to the cheap controller.