I was tempted by the UP3214Q, but 32" just seems way to big for my needs, both from a desk-space perspective but also because of PPI. What I like about my retina macbook is that it's 2560x1600 on a 13" screen (227ppi) vs the Dell's 140ppi.
The other win here is just the ease of switching inputs– if there was a standalone thunderbolt/USB3 KVM, or even a well put together DP2/USB3 KVM I'd happily buy that. As far as I've seen, though, most KVMs are one or more of: USB2 only, ugly and clunky, or crazy expensive.