The 'user friendly' thing to do is probably to go and find them the end answer, rather than referring them to somewhere else to look up the answer.
Yes.
I believe that this is not always the best solution. Although this is generally good idea when user is querying registry using some API with well-defined output, I can imagine that simple redirection of text- based whois output from other registry can confuse the querying software.
This is why RIPE and the other 4 RIRs should get together and replace the obsolete and inadequate text whois protocol. ARIN has already moved away from text whois with a RESTful protocol that outputs the whois directory info in an XML format. If all RIRs would support the same protocol, then referral could be done seamlessly. Even if the inquiry comes in on the obsolete text whois protocol, the RIR will be able to decode "foreign" whois lookups the same way as they decode "local" ones. --Michael Dillon