My experience with the CSRM collections is limited to the Charles Clegg collection. With that collection, you contact them and tell them what RR that you are looking for. Then they send you a list of photos, (if not a large number in the files) and a very low resolution scan. You pick the ones that you want, send them the money and a use restriction form (you have to ask them again if you want to publish) and they send you the high resolution scans.
I have no problem with this method. They saved the pnotos, have indexed them and scanned all of them digitally. This costs money, and in this way you help them to preserve these and other old photos as well.