Possibly OK for rear speaker but are they suitable for the main speakers? In a surround sound system the rear speakers are not as critical in terms of quality (or power) as the front left, right and centre speakers. The spec gives total harmonic distortion < 0.5% @ 1 W but nothing at 25W.
I assume that the two front speakers are either side of a room/tv/etc. so using one TX/RX you are only going to save one pair of speaker wires as both speakers would need to connected to the back of the RX unit via cable, with on speaker having a long cable. This is assuming that you not going to have one Tx/Rx pair of boxes per speaker.