There was another thread similar to this a while back, but I didn't see it in a quick search...
A newbie wanted to know about A2A's. He wanted to put it in just for reliability, since the stock W2A has a pump that can die and stuff.
From my understanding, most of the A2A's available are geared toward aftermarket turbos and stuff, and wouldn't be easy to just drop in place of the stock IC system. For the same cost as an A2A, you could buy all the other stuff you need to put your truck in the 12s, and like they said, you probably wouldn't see much/any difference in performance by switching to an A2A.
The W2A is nice in that the water can absorb the heat. With an A2A, the incoming air is only cooled by as much air that can pass through the A2A. The heat is dumped from the intake air directly to the atmosphere. With a W2A, the intake air dumps its heat into the water, then the water dumps the heat to the atmosphere. You can actually supercool the IC water to create MATs below ambient. If you do need an IC upgrade, you could even add aux cooler(s) (heatercore) or get a bigger replacement cooler. That will improve the heat transfer of the system for relatively cheap, while still allowing you to supercool if you want.