I recently bought a Spectratime SRO100 Rb. Very small, 11-19V, can discipline itself to 1 PPS input. I have Lady Heather working with it. It seems to be a very nice and capable Rb.
I noticed that the LPFRS serial commands are very much like some of the SRO100 commands, so have also added support to Lady Heather for the LPFRS. I just ordered an LPFRS to test that code.
I also did an adapter board to connect the SRO100 to my X72 signal breakout board (breaks out the signals to 5 BNC's and has a true RS-232 port). I will probably also do a adapter board for the LPFRS.