I don't think there is anything wrong with using the polyester. Not sure how well it washes and if you have to be careful with the dryer temperature. Polyester needs to be quilted more closely than some of the cottons. It also gives a fluffier look. You decide if you like it.
Warm and Natural or Warm and White represent only one type/brand of cotton batts - it seems to be quite popular. They are my favorites. According to the website, it can be quilted or tied up to 10" apart.
I'd suggest picking up a few different battings and try them to find out what you like.