You should've named it CPS 1337 or CPS Over-9000!
I'd personally go for a spherical bladder with a transparent and easy to disassemble reservoir. I'd also go with a pump more like the XP150's; it should be guided, but still allow you to apply direct force on the pump rod. Trigger is pretty self explanatory and common sense; use a 1-finger trigger guard, nothing else, period. We don't need tiny spaces to cramp teen-sized hands and larger. Nozzle should be mostly typical "combat" nozzles; 3x, 5x, 8x, 10x, and 20x are good output levels to consider. Having one riot blast is also acceptable, but not terribly necessary IMO. However, I never want to see fan sprays ever again; they're so useless it's not even funny. As for the reservoir, having it so large is not always a good idea, especially if you want to attach a backpack. Speaking of which, using large ball valves to open reservoirs would be much more friendly and less hassling than caps. In the midst of battle, caps always twist on incorrectly, and sometimes they leak if the blaster isn't well upkept.
We all know what a good blaster has. It's either got to be invented by homemade builders or the toy industry has got to improve dramatically or it won't happen. Homemade builders have had much more progress with this lately than any stock blaster in the past 7-8 years or so.