I was wondering this same thing OP. Last November I upgraded from an i5-2500k to an i5-4670k. I'm currently running OC @ 4.1ghz (1.18vcore). I'm a little disappointed that I haven't been able to OC higher. I tend to get crashes or run too hot if I even push it to 4.2ghz. I might have to do some more tinkering, as I know I've run at 4.3ghz in the past fairly stable. I'm able to run a lot of games very well at higher resolutions, even Zelda TP is playable for me now w/ the new hack (thank you!). I gave up on that game for about 6 months, as I just could not bring myself to go back to 480p on my Wii lol. I'm a bit of a performance whore though, and was curious if I'd see any improvment going to a Devil's Canyon. It looks like the performance jump would be negligible. I don't really care about the cost, I'm generally able to sell my parts for almost what I bought them for, so the upgrade $$$ would be small. I'd just really prefer not to have to spend the time installing a new Z97 mobo and re-do all of that stuff for an improvement in speed that isn't even noticeable. Looks like I'll be waiting for Broadwell or Skylake.
Windows 10 Pro 64-Bit | Core i5 4690K @ 4.3ghz | eVGA SC+ ACX 2.0 GTX 980 Ti (x2 Sli) | Noctua NH-D15 | 16GB DDR3-2400 ram | MSI Z97 Gaming 5 | 500 GB Samsung 850 EVO SSD