Hi, well the 2014 814 actually has those Nanoweb HD strings which are a mix of light and medium. The 516 are mediums. I'm actually finding the 516 an easier guitar to play and also finding that I prefer the sound. I've only had the 516 for a few days but have played them both everyday for several hours and find I want to play the 516 more. I still love the 814 both looks and 'playability' but find the 516 more to my liking. I'm primarily a strummer but doing more finger picking all the time and both styles work well on the 516. So, I agree with you on the preference for the GS.
wps,
I too have 2013 814ce as well as the 2014 516ce-FLTD, which is almost exactly the same as the MF version, minus the bear-claw top and the armrest. My experience with the 516ce-FLTD vs the 814ce is very similar to yours. I just love the balance, tone and playability of the 516ce-FLTD. The combination of the Tasmanian Blackwood and the Grand Symphony body style just compliment each other so perfectly. The tone is so just so lush, without the mid-range "scoop" that the rosewood has.
I too am primarily a strummer, but do a little finger style now and then. I am impressed with how well the guitar handle both styles as well how responsive it is to both a light touch as well as a heavy strum. Again, the tone is just amazing to me. I find myself reaching for the 516ce-FLTD about 80% of the time these days. It is truly an exceptional guitar.