I've seen the new Givi Trekker hard cases at the NEC and they might be just the job for me -later this year. They open at the top or you can open the whole side too - handy. Although they're silver and black, some matt black would soon tidy that up-or you might like the silver! I think they would suit the Roadster - a bit tougher than the rest!
The back is flat enough to suit the Easybrackets too. If they get a bit slack and rattle, as they will I guess eventually, just get some 5thou shim steel washers and you'll be fine. Extra weight in them will just help stop them rattling.
- anyway they'll never fall off
Worth a look