There you have it! We hear end users every day ask for 512MB mid-range cards and sales guys refusing to offer advice. 512MB on a mid-range card simply doesn't offer any benefits. While the extra memory comes in handy at resolutions like 1680 x 1050 and 1920 x 1200 with high detail settings, the fact that these cards simply can't do it means that it's a waste. For example, we might move up to 1920 x 1200 and a 512MB card offers us 11 FPS vs 10 FPS on that of an overclocked 256MB. While that 1 FPS equates to 10% the bottom line is no one can play a game with an average of 10 FPS or 11 FPS.
Does this make Palit a bad company for releasing a 512MB version of the card? No! The bottom line is it doesn't matter what you tell some people, they will be convinced that a 512MB mid-range card is so much better than a 256MB one and if Palit didn't have a 512MB offering the user would simply go off and buy another brand.
The main problem with people who purchase 512MB cards is that they don't have the money to get the next model up. For example, having a look at pricing in Australia the HD 2600 PRO 512MB (or Super) comes in at the same price ($135AUD) as the HD 2600 XT 256MB overclocked (or Sonic). Today we compared two cards that offer the same core, imagine that you now step back a model, performance is really going to be down. It's simply too hard sometimes to sell a HD 2600 XT 256MB overclocked card to someone who has $135 AUD and wants a 512MB one. They end up walking out with a HD 2600 PRO 512MB which is considerably slower than that of the overclocked HD 2600 XT 256MB.
This dives even deeper sometimes with people telling me that an 8600GTS 512MB is better than an 8800GTS 320MB simply because there is more RAM.
People simply have to remember that on a mid-range card raw speed is generally better than more memory. It isn't until we move up in the range and hit cards that are able to perform well at resolutions like 1920 x 1200 and above that we can see the extra memory on a card come into effect.
The most important thing to remember is to buy smart!