I think you're right that the DD and 20th Silo may have kept people from buying 2006 LE. This time, though, there is the 20th SR5 and the BFRs (including JP, Luke, potentially AL). If you think about it, that's 4 different models to distract people from buying a 2007 LE. So, I don't know if it will be any different this year.
When did the ordering window for 2006LE close? BP is saying that the 2007 ordering window might end in late May, but I don't know if that's early or not, if it's due to the Blue Dawns selling better, or if it's due to other models (i.e., BFRs) that need to be produced too, etc. Maybe, it's because the BFRs were ordered in the thousands.