I can play some decent bitrate BD rips on the Roku 2 via plex as long as I'm using Ethernet, but the audio is transcoded to Dolby Digital. I've been having fun with openELEC XBMC on the Raspberry Pi, which runs on the same Broadcom SOC as the Roku 2, but without the restrictions of the Roku OS. You can connect to a Plex server if you like with PlexBMC, but it also streams well via SMB and NFS. You can do passthrough of DTS-MA and DD-HD core audio with fiddling, but you won't get HD audio out of the Pi due to lack of codec licenses. If you need to play BD ISO's, then the Dune, Popcorn Hour, or any number of cheap Realtek 1185/86 boxes will do just that.