ok is there a consensus yet? i'm debating these two cameras too. i need a camera, housing, and wide angle lens by mid-august. decisions, decisions.
I doubt you'll ever get a consensus here! 
But it really depends on whether you need/want/want really badly, the flip macro lens.
If you do, at the moment, L & M and the XR520 is the only combo.
This totally changes the functionality of the housing underwater. Sure with a good wide angle you can still get Macro, but nothing like the magnification of this flip macro lens!
That being said, gates will have the XR520 housing out next month sometime, so they might integrate one? 
As for housing choice, it depends on how long you want/need to get get to know your new system before getting into the real world with it. I have a big trip in mid August too, so wanted at least 6 weeks with it before flying away with it. New camera/housing/lights/software for HD... it's a lot to learn!
It is a hard decision, but really comes down to how much you want to spend. Top of the line the Light & Motion ($4200) and probably the Gates (still to be advised).
The pricing of the Aquatica is cheaper than L & M and probably the Gates at around $2400 but is still more than the Ikelite which is only $1300, and to be honest, the Aquatica having those buttons covering your screen when you're trying to shoot could get annoying. But it makes it easy to access all the touch screen controls so is personal preference.
The Ikelite is the best priced, and still gives you access to the Touch Screen on the camera which you need for White Balance, so this seems to be the best value for money (if money is the deciding factor). Have a look at dimensions and weight if you are going to fly with it though, as this can become a negative.
I went with the XR520 in L & M, but only because I "really" wanted the ability to use flip macro and superwide angle on the same dive.
If I didn't want that, I would have gone for the Canon HFS 10 for 4 reasons.
1. Dealing with solid state "Memory Cards" is always going to be more reliable than a hard drive long term. (Get top quality cards, never cheap).
2. If you ever flood the housing, you don't loose every frame you shot since you last downloaded to your PC! Just what's on the card (and maybe not that if you can dry it out quickly!)
3. More natural colour performance from the Canon, (by quite a bit looking at the reviews) and records in 24Mbit/s rather than Sony 16.
4. Easier one touch white balance, as it can be done through the electronic controls on the housing, rather than the touch screen (if your housing has that type of control). L & M do, Gates probably will.
But it's not like the Sony is horrible, it really is an amazing "little" camera, and it is "slightly better" at low light situations with noise etc) than the HFS 10, but they both are very good at manual white balance underwater from what I hear.
I think the call is a hard one, and as always, there are compromises whichever way you go!
Hope that helps a little!