I just went from 2010 enduro to 2015 trance sx (27.5). What a difference! I lost 20mm of travel in the rear but you would never know it. Maestro suspension is completely different than specialized fsr, very supple and better pedaling platform.
I also would wait one more year, if possible. Try to get something 2014 or newer. And if you're looking to go 29er, im not sure giant is the way to go. The majority of their recent focus has been on 27.5 and I've read their first try at 29ers did not have the best feeling, geometry wise. Also the direct to consumer market is growing and offering some incredible value...