Respectfully, i'd have to kind of disagree with you here. I know you like NV (I do too) and there is nothing wrong with that, but that may affect objectivity somewhat. Here's my experience having used both NV and AMD extensively - First, you can't really compare different architectures on a clockspeed basis. Additionally, at stock settings the 770 and 280X start at roughly the same speed with some architecture specific games showing an advantage one way or another (blizzard favoring NV, and Square-Enix favoring AMD, for example) yet overall, we can agree that the stock settings for the 280X and GTX 770 result in roughly the same performance or within 1% or so. (Hardwarecanucks tested a "stock" 280X which was overall 1% slower excluding overclocks). So let's say they're even at stock speeds. I disagree with you in terms of overclocking - i've seen numerous reviews showing both the GTX 770 and the 280X scaling 10-12% from overclocking, and let's not get into clockspeed semantics because that doesn't really matter. Again, different architectures, different clockspeeds, not an apples to apples comparison. What is important is the performance gained with any overclock, and if you look at overclocking at guru 3d you'll find that their Gigabyte and Asus model 280X cards are gaining roughly 10-12% performance from overclocking. This is not dissimilar to the GTX 770, which also gains a similar amount from overclocking.
I think the GTX 770 is a great card. But performance wise, it really is a wash. I'm actually surprised to see this argument head into clockspeed and overclock territory, because the websites that truly push high overclocks (guru3d and HardOCP) have shown excellent scaling on both cards with overclocking. Easily 10-12%, maybe more if you're lucky. Therefore since both cards are similar performance wise at stock, it is safe to say that they're both similar once both are overclocked.
I just disagree with you in the strongest terms with your suggestion that the GTX 770 scales or performs better when overclocked. The 280X overclocks well too. The stock is 1000mhz and I know the original 7970CF cards I owned previously did 1100+mhz no sweat. I expect the same of the 280X, and indeed this is the case if you look at all of the aftermarket 280X cards being reviewed.
That isn't to say the GTX 770 is bad. It's an awesome card. I do feel it's a little too expensive, since the 280X is the same in terms of performance. Like I said you can nitpick results with games that favor either AMD or NV's architecture, but overall averaged out they are the same speed. The price gap between the two is too large, however.