Can this scheme be used to balance an unbalanced output transducer?
If you make Rx = Rout and R1 = R2 then yes, this is a fairly standard trick, but you must make the impedance match. 

Note that higher input common mode impedance reduces the sensitivity to source impedance mismatch.

The search term you want is "Impedance balanced output" and you will find a ton of stuff from the audio industry (that likes this because it is cheap!), but it is just as applicable to any other sensor.