I recently upgraded to Family Tree Maker 2012, which allows me to synch up with the tree I store on Ancestry.com.
It's only been a few days, but I already appreciate the feature. Not only do the two "versions" match, but the synching also covers photos. With older versions of FTM, I could download a gedcom from Ancestry.com, but that wouldn't incorporate any of the photos (have thousands) that I've either found on the site or uploaded myself.
I still prefer to work on the site -- Ancestry.com's hints work better in an online environment -- but I love the fact that I have a 100% accurate backup on my computer.