I would like to know if there is a power output difference for the RFOUTB signals if we pull up the outputs with 50 ohm resistors or with RF chokes, as your data sheet indicates for single-ended outputs.

The datasheet guarantees the output level of -4dBm to +5dBm for a single ended output power with an RF choke to supply. This does not mean that a resistive pull-up cannot be used but there is no guarantee that you would be seeing the same range as when the inductive pull-up is used.  You may or may not be seeing the same range of output. 

If the output level range is crucial in your design, it is suggested to use the RF choke configuration for single-ended output.