Yamaha NS-IW660s make excellent rear or side in-wall surround speakers. You will have no shortage of volume! I have two as side surrounds and another two as rear surrounds in my movie room.
The NS-IW470 is a step down in performance (40W RMS vs 50W RMS) but are actually being sold for more than the 660s at the moment..
For fronts I am using NS-IW960s and these are being heavily discounted at the moment. They work great too. Two 5 1/2 inch woofers and a 1 inch tweeter, 75 watts RMS, 150 watts peak. I use a third mounted in a shallow home-made box screwed to the wall under the TV for the moment as a centre. If / when I get a 4K projector and screen I am going to mount two of these behind the screen as I have a wall stud right in the middle of the wall where one speaker should go. Otherwise I would use just one. The 960s are probably way too big for rears or sides unless you have your own full-size cinema though!
You can look at cheap copies from $100 a pair, or buy similar products from Klipsch etc. for similar prices up to $2000 PER SPEAKER. The choice is yours, but I really don't see the point of spending thousands in my 6 m x 4 m movie room, given they are for surround sound effects, not audiophile listening.