My wife has my old GNex now and running AOKP Milestone 1 (newer Nightly builds should be just fine) with Franco Kernel (probably Milestone 2) and it is silky smooth. OCed and undervolted at all speed phases no problems.
I thought I must have missed something too. LG Optimus G2 or Nexus 5 maybe, but they don't have all that much over the One/S4. Same display but Snapdragon 600 at best, definitely considered same generation in my opinion.
I remember when they first announced it, I saw the prototypes at CES (2009 I believe) and they were planning on charging $1500 or something stupid. The actual released model is much cheaper feeling, the prototypes were built like tanks. Cool case nonetheless!
Finally got my Nexus 4 setup how I want with PACman 22 ROM on T-Mo's $30 "unlimited" plan. I paid $23 for $30 refill cards on eBay.
Hard to beat $23/mo for fast data and no contract.
That way I can grab the "Nexus 5" or whatever they call it, when it comes out and flip my old Nexus 4 for $200+ on eBay :p