I have a coworker that had an air source water heater installed in his basement...he said it works well and cools his basement down pretty good! I happen to think that it would work pretty well.
If there are rebates available from my local utility company, I might consider doing it when my water heater is due for replacement. In my scenario, I have all my equipment in an A/V room, and I have a bathroom exhaust fan that is controlled off a line-voltage thermostat. That exhaust fan sucks air past the rack and blows it into my storage room (that houses my furnace and water heater). It cant work much better than that.
I havent done much research yet, but one thing to think about is if you are using a bunch of hot water, you probably are not down in the theater rejecting heat from your electronics. I suppose a dishwasher or a washing machine could be running while you are watching movies, etc. What I am getting at is I dont know how much $ savings you would see, so it would be hard to calculate a payback. If your utility company gives you a rebate though, it could help it be financially feasible.