Exactly. I printed off my transfer notification, so it's paper I can present. The paper, even a registration certificate, it can be argued, is simply documentation of the certificate, not the certificate itself. The certificate exists in the CFP hall of records, or whatever. As far as I know, the transfer notification contains all the information the registration certificate contains.
Also, the notification itself says I need an ATT to take possession of the firearm, nothing about waiting for the "official" registration certificate. I take that to mean I can drive down to the seller's house and get my firearm immediately, which I believe is the common practice. If I can do that legally, I should be able to take it to the range legally. I think the CFOs that say you can't are blowing thunder.