I think with proper lighting reflection is not a problem with plain glass. How does acrylic hold up to cleaning and with what? It is lighter than glass so if shipping is an issue it might be worthwhile. I would also go with the sharpness folks.

At exhibitions I have attended it appears that most viewers are interested in the content of the images as opposed to technique. A serious purchaser would probably scrutinize more closely and possibly want to see the image unframed.

http://www.jeffreyglasser.com/