I've got a mostly full set of MOLLE gear as part of my patrol kit. I like it well enough. I don't really like the canteen pouches though, getting a canteen cup in or out of them is a real pain in the rear. I hated that the ALICE canteen pouches were not covered. I may look at some commercial canteen pouches to see if they fix the cup and stove problem.
A small pack with a hydration bladder is a nice addition, or the MOLLE pouch that attaches directly to the vest. It allows more water to be carried and can provide a bit more room for a couple of items. I still carry two canteens even though I have a 100 oz Camelbak - the canteens are a lot tougher than the Camelbak and they make a good place to keep water that I have put purification tabs in, then it can be poured into the Camelbak.
I like to have an extra canteen pouch with a 1 quart/liter Camelbak or Platypus bladder in it. This allows me to pour any part canteens into the bladder so that there is no sloshing noise.
For smaller loads, like hiking, a MOLLE vest and pouches works really well. The older ALICE system works good as well, although it isn't as customizable. You will always have your survival kit and a bit extra if you have a LBE/LCE system, and that is a good thing.