The CPS-3000 is one of the most intimidating supersoakers around.
Its large backpack enable you to keep on fighting when everyone else already has to refill. The range is similar to the 1000/1500/2500, though I have the feeling that 3ks normally go a bit further than a 1k.
I've heard of backpacks ripping apart when people ran with them, though I've never actually seen this happening (and I saw a lot of people running with 3000s). Another problem seems to be the connection between the backpack and the gun, as I've seen the plastic bit that is going on the gun breaking apart on two different guns.
As to the 4 different nozzles: 5 times gives the best range and conserves your water, 10 times/20 times gets people wet, but has a strongly decreased range, typhoon gives three nice streams going in all directions, but I've never seen any real use for it.