OK, here are some questions:
Are you using PC or Mac?
http://74.125.47.132/search?q=cache:tAbmd2CNU6UJ:mograph.net/board/lofiversion/index.php%3Ft19368.html+after+effects+need+high+end+graphics+card&cd=1&hl=en&ct=clnk&gl=usSo, 1st, double check to make sure the cards you are looking at are supported by the products you want them to be used by.
Are you sure you need this much power and will the rest of your system keep up?
Here is a test that contained the 2 setups you are interested in:
http://techreport.com/articles.x/16229/141 last thing to consider, how fast do you want the upgrade and what are you willing to pay? You say you have about 4 months until you can buy the second 260, so if you choose the 285 will that be in 4 months too?
I would say if you are gonna wait 4 months to get what you want, wait for the 285. You never know, it may be cheaper then. Plus, if you choose 260s in SLI, where do you go when you need to turn it up to 11? By the time you outgrow the 285, SLI THAT.
Just my thoughts and opinions.