I have this on my k1300s. Installation is fairly straight forward. There are a lot of screws holding this thing on. Quality is good and it does fit into the design/style of the bike.
I bought this about the same time as my bike. If you have the standard grab-rails, you will remove those and put this rack in its place.
It has an adapter place that appears like you should be able to replace it with a BMW bag. Though I haven't found whatever bag that is. The current tail bag for this bike just slips over this luggage rack and straps to it.
I think if you want to get non-BMW cases, you could also look at the SW Motech.
I had this on for a while so I could strap a bag to it to give my wife a backrest. It worked well for that.Rating: [4 of 5 Stars!]