Yes, it's a pity. HardOCP do go into more detail about the specifics of the gameplay experience than other sites, but the analysis is largely subjective. Some more quantitative analysis of framerate irregularity ("microstutter"), and VRAM limitation would be appreciated from all the major review sites. But as you have pointed out, they are married to the average-framerate bar-charts that they have been producing since the dawn of time.
Regarding the VRAM limitation issue that this thread is focussing on; it is very much game-dependent, and resolution / anti-aliasing dependent. In the case that the game is consistently using more than the total VRAM allocation of the card, there will be near-constant DRAM -> VRAM paging, and the average framerate will plummet. This will be clearly visible on average-FPS graphs. However, in the case that the VRAM limit is close to the threshold, there will be only certain game scenes where the VRAM limit is reached, leading to relatively infrequent cases of paging, which will manifest as small pauses or brief periods where the framerate drops dramatically. This is extremely disruptive to gameplay, but may not have a significant effect on average-FPS benchmark scores.
One final point to consider is that the 1Gb card has a higher memory bandwidth (not just memory capacity) than the 768Mb card. From the benchmarks posted, it seems that this tends to offer around a 5% average performance bump (between 2% and 10% in almost all cases). However, you should also consider that the GTX460s are highly overclockable cards - this is one of their main selling points. The GPU core tends to have a lot more overclocking headroom than the memory, and therefore in an overclocked configuration the cards can be more memory-bandwidth restricted than at stock (since the core clock is increased disproportionately from the memory clock). In this case, the increased memory bandwidth of the 1GB card may become more valuable, and lead to a greater difference between the two cards. If anyone has access to comparative benchmarks from heavily overclocked 768Mb / 1Gb GTX460s, it would be very interesting to see if this bears out.
Anyway, to summarise the whole thing: It's clear that the GTX460 1Gb offers better performance than the 768Mb variant. Whether it is worth the extra cash outlay will depend strongly on the needs of the individual user: The resolution they game at and how much AA they intend to use, the suite of games they expect to run, how tolerant they are to in-game hitching, how heavily they intend to overclock their card, and how much headroom they want to leave in view of potential future releases. I don't think it's possible to boil down all these factors into a "one size fits all" statement about which is better value.
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