It's really a toss-up
I've read a lot from both camps on the AirDog vs. FASS system. In my *opinion* both are of excellent quality. However, I don't really think either one is very well thought out (again, my opinion). What are you getting for the price? You're getting an aluminum block machined to accept a couple spin-on filters with a lift pump attached to it. What you don't get is:
-An option for a 12v heater
-Any kind of adjustable pressure regulator
What's the flow rate vs. pressure for the pump? Can these systems be submerged in water (if you mount it beneath the frame and try to ford water, will you be in major trouble?). Why do both these systems bypass the stock filter canister, when that canister comes with a nice 300W heater and a 10-micron filter? In my *opinion* it would be more appropriate to retain the stock filter canister (you did pay for it, after all) and add the improved filtration from these units.
Nevertheless, for those who want a simple, complete, bolt-on installation to replace the stock lift pump you really can't beat either FASS or AirDog. I'm not sure who's been running either one for a long time, so longevity is not immediately apparent, but it seems they'll probably last longer than the stock LP.
In my *opinion* you can do better (better is very subjective, I know) than FASS or AirDog by designing and building your own system. But then, that's true with almost everything you can buy: either pay someone to build it for you and be happy with what you get or build your own and get something that exactly fits your needs. Same reason so many people build their own computers.
If I were *forced* to buy either an AirDog or a FASS, I'd probably buy the AirDog. Probably. That's just my *opinion*. Best of luck with whatever you choose!
-Ryan
