Hi Ben and Phil, as you may know (Phil certainly knows), I'm on the editorial board of IJC. Phil is right that it can be rather slow (though faster than certain other climate journals!). Nevertheless, IJC really is the preferred place to publish (though a downside is that Douglass et al. may have the opportunity to have a response considered to accompany any comment).
I just contacted the editor, Glenn McGregor, to see what he can do. He promises to do everything he can to achieve a quick turn-around time (he didn't quantify this) and he will also "ask (the publishers) for priority in terms of getting the paper online asap after the authors have received proofs". He genuinely seems keen to correct the scientific record as quickly as possible.
He also said (and please treat this in confidence, which is why I emailed to you and Phil only) that he may be able to hold back the hardcopy (i.e. the print/paper version) appearance of Douglass et al., possibly so that any accepted Santer et al. comment could appear alongside it. Presumably depends on speed of the review process. If this does persuade you to go with IJC, Glenn suggested that I could help (because he is in Kathmandu at present) with achieving the quick turn-around time by identifying in advance reviewers who are both suitable and available. Obviously one reviewer could be someone who is already familiar with this discussion, because that would enable a fast review - i.e., someone on the email list you've been using - though I don't know which of these people you will be asking to be co-authors and hence which won't be available as possible reviewers. For objectivity the other reviewer would need to be independent, but you could still suggest suitable names.
Well, that's my thoughts... let me know what you decide. Cheers Tim Dr Timothy J Osborn, Academic Fellow Climatic Research Unit School of Environmental Sciences University of East Anglia