I've been trying something like this with my Raleigh Twenty. I got the Bike Friday trailer frame and hitch (not the luggage). Picked up a thrift store suitcase, attached the trailer frame. The bike fit in with pretty extensive disassembly. The trailer wheels were not fitting in easily. So bike and trailer parts, except the trailer wheels, went into the suitcase. I used a duffle bag for the trailer wheels and all my camping gear, clothing, etc. It seems the capacity for my duffle bag was very close to the capacity of the suitcase, which makes it very handy. At my destination, I assembled the bike, attached the trailer frame to the suitcase, and emptied the duffle bag into the suitcase trailer. If my suitcase had survived the baggage handlers without damage, it would have been great. As it was, it worked, but I needed a new suitcase the next time around. The next time, the suitcase came through fine, going to and from my destination with one transfer on each end of my journey. My bike didn't work properly, but that is not the fault of this system, but rather a problem with trying to use cutting-edge gearing systems on a 40 year old bike frame.

So things that I've learned from these trips that might inform your luggage choices:

While I like the matching luggage, I would still prefer a soft, collapsible bag for non-bike items. It holds more, weighs less, and folds up out of the way when you transfer everything to the suitcase trailer.

Waterproof is nice. I know my first suitcase trailer was not waterproof. I doubt my new one is, but it hasn't been tested yet.

I hear that zippers are a failure point when loading large cases up close to the weight limit. I haven't had a problem with mine yet, but I also add a luggage strap to take some of the burden off of the zipper. I can't tell if your case uses a zipper or not. I imagine a zipper also can create an entry point for water.

In spite of having a fairly large case, I still seem to end up with more gear than the case can hold. I like the idea suggested earlier in the thread that the case be made with the idea that more items could be carried on top. This could be as simple as strap or bungee attachment points. Carrying items on top of my suitcase trailer has never been a problem from a weight perspective, but it can be tricky to get items securely attached. On the other hand, I pack too much. It's probably a better policy to limit your luggage to what can easily fit inside the suitcase trailer.

On the whole, I like the idea of your system. I like the Bike Friday system, too, but it does sometimes look a little expensive for what you get. I also like how your trailer breaks down. The trickiest item to pack in the BF system is the longest piece of the trailer frame. I'm sure it fits fine in their, preferred suitcase, but for ease of packing, I wish it broke down a little smaller.

Good luck. I think it's a great idea.