... well, I certainly did. As usual I was taking the shortcut. Once snapshot was created, I downloaded the .BAR file, renamed it to .ZIP, extracted it, found the .RPD file in extracted folder structure and ultimately opened it. It worked for me so far, but I learnt my lesson a couple of days ago. I don't know, maybe I wasn't paying attention, but the case was: "Invalid password".
Basically I found a solution quick at Oracle Support under this very link, however, let's take a look at the whole process.
When snapshot is created, one would usually download the snapshot in the form of the .BAR file.
After the snapshot password is provided, download can begin. In my old habit I then simply renamed .BAR file into .ZIP file which is then extracted.
In the extracted folder, .RPD file is located in the \datamodel\rpd subfolder (in the screen below, I copied default.rpd file to Desktop folder).
And if you try to open the .RPD file this way from Model Administration Tool (hey, I didn't see that rename change either !!!), it will return Logon failed error.