Well, rip-123 will always be correctly addressed as ripe-123. It's just that ripe- doc-1234 would could be called ripe-1234. I don't see any confusion arising from that and the normal document churn would take care of any potential confusion, anyway.
The confusion is that, for the next 25 years or so, people will be wondering what the relation is between >ripe-<foo> and ripe-doc-<bar> documents. Which one replaces which other one?
So again, please don't.
A document is already have several names assigned to it (ripe-500 = Policy Development Process in RIPE) and has already put in different "categories" (Address Policy and Address Management Related Documents, Recently Published, Current Documents - concerning the ripe-500 example) and has several different meaning of access (web, ftp...). So it is not big deal to have one more "supername" near to the previous name. People who can't deal with simple understanding of "names" and "numbers" are not working with documents, explaining and regulating much more difficult and complicated things.