Thanks for the repost, I was here back then but wasn't very active so missed it the first time.
First of all a very good song.
And man, those vocals sound fabulous! Two great singers of course, but the vocal treatment is superb. Are you using a bit more reverb than you normally do? I couldn't imagine them possibly sounding better, well done.
Killer job on the production and mix, one of your best IMHO.