If I got a request from an agent for an exclusive submission of the full MSS I would send it along, but not mention their terms. This is for two reasons.

1) If that agent took three months to send out the request then I might have already sent the MSS to another agent. I won't want to put off the second agent, but I won't want to risk the chance that the first agent may still reject it. Some agents use the word "exclusive" as par for the course. The reason is that they don't want to have their time wasted if the MSS is being considered by someone else; they don't consider that exclusive submissions are more of a waste of time for the poor sod submitting to them.

2) If you get several agents interested and they all want to take it on, then you get to consider multiple contracts, which according to Carole Blake, is the position we really want to be in: her advice is never to take the first contract offered to you just because its a contract. But if you go along with exclusive submissions, that would mean you could be holding onto that contract for a good few months before you get another.

That's my twopenneth.

Colin M