I just upgraded from a 104hp 3u skiff to the Arturia Rackbrute 6u and I love it. The size and form factor are perfect and the stand/handle is great for setting it up to play at different angles. Enjoy it! I think you will like it.
If for some reason you have to replace a ribbon cable, they are readily available from most websites/stores that carry modular gear. In the USA, Perfect Circuit, Sweetwater and even Amazon have them(I just bought one to replace a bad cable on my 2hp Pluck from Sweetwater for $6 shipped). There are 2 flavors: 16 pin to 16 pin and 16 pin to 10 pin. Like others have stated, you will get a ribbon cable with each module and they are usually paired with either flavor cable depending on the design of the module. Also, you will almost always get 2 sets of screws with your module to mount it to your rack, a set of 2.5mm and a set of 3mm. The Rackbrute takes 3mm and comes with 8 screws to get you started. I would recommend grabbing a set of 3mm screws from amazon if you find yourself losing any of them or if you but second hand modules.