Whenever you have a question about what an increase in wing area will do to your pitch stability, the geistware CG program is a good place to look for answers. Most times when you're only increasing wing area by around 6%, the only thing you'll see is a narrower CG range that's a touch forward from where it would be otherwise.

This program will give you all the figures that you'd want to look at to make the decision. Run it with and without the increased span and compare.
It'll take your simple measurements and instantly figure out your areas etc etc.

http://www.geistware.com/rcmodeling/cg_super_calc.htm