I had the first generation (2015) Spectre x360 13 until October 2016, i7 16gb RAM, 512gb SSD, used it with HP Active Pen and very pleased. Suffered water damage and, under the HP Care Pack I had bought, HP gave me a full credit for my purchase price (an option they gave me, as components for repair would take them over a month to receive). So I replaced it in October, 2016 with the Kaby Lake generation of the x360 13, and 256gb SSD (as there was a significant ship delay for the 512gb SSD). No pen digitizer option available (sigh). Was dearly missing the pen until the new 13 and 15 inch versions came out, with pen support and dark ash silver color scheme. So I handled the 15 inch version and decided the graphics performance improvement over the 13, and faster RAM and prompt availability of UHD display, made it the choice for me (even at 4.4 pounds vs. 2.9 for the 13 inch model). I can still read the news in tablet mode without struggling with the additional weight, sitting on the sofa like the Dad I am. BTW I'm selling the Kaby Lake 13 inch pen-less model soon on eBay for a competitive price, including Pelican hard case and premium leather HP soft case (not the stock sleeve that comes with the unit, which I also have along with original boxes).
I would recommend going to your local Best Buy and handling the 13 and 15 inch models to see how the size and weight difference works for you.