I don't have experience with the monoprice units, but they tend to give value for price as an organisation.
However, I have Paradigm in-ceiling at home and rbh in ceiling at the ski cabin.
For background listening, they are more than adequate. The Paradigm units in our kitchen are great and can handle 50 watts if you feel a need to blast and they hold it together. While not audiophile, I can tell the difference between a mediocre and a good source with them. (Squeezebox Touch playing lossless files, Beresford Caiman DAC, Cambridge 65 wpc integrated amp, Rotel CD player, Rotel 6 channel amp)/
The rbh speakers at the cabin are playing through a Russound whole home audio system. I have pairs in 5 rooms. The Russound amps are small little digital amps. I get the sense these are pretty efficient speakers, though I have not driven them hard, they play at background levels for days. Turn them up and they respond fine. I have smaller units (can't recall exact model numbers) in bedrooms, with larger units in the living room and master bedroom/bathroom area. The sound, especially from cathedral ceilings, is very good and room filling. While the source tends to be iPod ripped at 256 kbps, they system is smooth, room filling, but certainly not "thumpy" .
I woud not go in-wall or in-ceiling for critical listening, but for hidden, background music, either of the ones I mention are more than adequate.