The directional tweeter is more important than a directional woofer. Fully directional speaker is better, but not required. If looking to do the traditional side surround, then the speakers should be placed on the sides of the listening position. I prefer to have the speakers set at least 4' away allowing the ambient sound field to be created. Surround sound is meant to add to the experience, not over power your front stage. If they are too close, they will become distracting.
Regarding speaker preference, I guess I would stick with the Polk if this is your budget and these are your options.
If there is a room above the the living area where the in-ceiling speakers are to be installed, you will want to create a back-box of some kind to help prevent the sound from penetrating into the upstairs. It may also help with SQ.
just my 2 cents
My set up
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