Damn, I dunno, that really sucks.
How close are you and your PD/Chairmen/Advisor (or all of the above). If you're pretty close, you could probably just set up a meeting and bring it up, at least that's what I'd do, but my PD (who is my advisor) is cool as hell.
If it were me, and I had to decide without help, I guess it would depend on how I felt I ranked with my home vs my number 1 and the AI. If you think you're guaranteed home as a backup, and not much shot with one of the others, then there you go. If home isn't going to rank you anyway...or more importantly if both your AI and number 1 love you, then maybe you could risk blowing off home. I dunno, that really sucks ass, you've scared the crap out of me now in fear of that happening to me (although that's tons better than not getting an interview from you're home program, which could happen).

speak to the chairman at your home program to air it all out. if he's worth 5 years of your life, he'll help you work something out. or he may indicate how they intend to rank you, which could help you decide which one to take. just be sure to remind him how much you love your roots, to cover your arse. my opinion + $3.75 will get you a latte.

i'm in a similar situation.........its sucks......when push comes to shove, you have to think where you will be happy for 5 years....thats what i am trying to convince myself, but it is definitely not an easy decision........i'd say i'm glad to not be in your shoes but i am.........one tough decision to make