I have one of their Ultimate Traveller bags. It's really well made, especially for the money. It's sturdy, well padded, and seems to be made with quality materials.
I have a few gripes about it though, for what it's worth. I was told it'll fit four AD600 Pros with handles but that's not quite true. The handles aren't out yet, but the AD600 Pros are about an inch and a half too tall for the case. You can close the lid zipper if you really push down on the lid, but it strains the zipper and offers little impact protection on the top and bottom because of the tight fit. There are shallow pockets inside the lid and on the front, with emphasis on shallow. The AD600 Pros will fit nicely if you remove the batteries, but then won't accommodate them if you add the handles later on.
The design criteria for the case was to make it as big as possible while still meeting airline carry-on size regulations. It does this very well. However, for my needs this case would be a lot more useful if it was a few inches taller and about 20% larger all around. I'd also like to see this case with two handle loops so that you could easily pick it up to move it. As it is, you have to zip the lid closed or fasten the snaps in order to use the handle.
This case would probably work out really well for you as it seems to be designed to fit the AD600s. They fit in there nicely. I agree with the above comment about packing strobes separate from your stands. Most all-in-one strobe + stand carry cases are too shallow to hold your strobes vertically and laying them flat horizontally takes up a lot of space. They're also usually too short to fit decent stands that you'd trust with your AD600s. For stand bags have a look at On Stage or Gator bags. They're well made and reasonably priced but not that suitable for air travel. If you need to fly, want better protection, or need to carry taller stands, have a look at Fibrebuilt hard tubes.