Hi,
i tested the epson tmp20 BT and the bixolon sppr200ii bt successfully via opos.
NOTE: If you use the Bixolon OPOS it should be the only installd opos. there are problems if you install epson opos and bisxolon opos on one device.
I would prefer the epson tmp20 bt because they are fastern as the bixolon. You have to wait about 20sec for the first print with bixolons, the others are nerly the same.