I highly recommend Scale Sound Systems. J.T. has a wide selection of various enclosures, as well as just the sugar cubes. All of them sound great and he's willing to provide suggestions if you particular model is not listed.
His order desk will be open again on Thursday next week as he was awaiting some supplies.
I use the CoEval speakers wherever they are available - choose the 4 ohm version to work best with RailPro. Even if a CoEval version is not listed, just ask and he'll let you know if he can do a CoEval version.
I've watched a video J.T. provided of a SW1 install with one of his sugar cubes and it sounded just like a CoEval install.
Drop him a line and he'll help you out.
I have no financial connection with Scale Sound Systems, I'm just a very satisfied customer!