I know I've got to get over my camera shyness to do the subject of Windows tablet art justice and remain competitive in this tech review space. But in the meantime, I hope you won't mind when I link to videos that do a great job for me.
That's the case with this excellent comparison of the Surface Pro 2 and the Sony VAIO Flip 13 by Lisa Gade, Editor in Chief at MobileTechReview.
In just under 17 minutes, she exhaustively reviews the pros and cons of each device and reaches much the same conclusions I did: if portability and Photoshop are a must, go with the Surface Pro 2 and if you need an ultrabook with art capabilities, go with the VAIO Flip.
Like Lisa, my first observation about the Flip 15 was the excessive noise coming from the overtaxed fan, but I recently turned off indexing and now the fan rarely turns on. I also was having problems with frequent loss of pen and touch control which appears to have been resolved with a BIOS update from Sony's Japanese support site.
I've cued the video up to begin with the pen technology comparison, but by all means watch the entire thing when you have time to spare.