I use, and recommend the use of poly/cotton for Project Linus and other charity quilts, the reason? Because of their being what they are they undergo such much more washing and laundering than normal quilts, sometimes every day, and poly/cotton is manufactured just for that, multi laundering.
For us die hard quilters it may seem wrong but remember these are not "Heritage" quilt they are "Huggles" for a poorly kiddie-wink and do a super job.