I have used natural colored batting in white quilts without it being noticeable in the end. It did Not dim the whiteness of the quilts. If he likes the weight of the guest room quilt I would try to use the same batting... But, if the guest room quilt is pieced, it will be heavier than a wholecloth-- the piecing creates, adds to the weight. So you need to take that into consideration and maybe try to find a heavier batting. Warm & natural is pretty heavy it might still be enough as long as the fabrics you chose are fairly heavy too- not this, lightweight.