yes, the harddrives themselves, each port has its own limit, the chipset has a limit aswell but 2 decent ssd's aren't breaking that limit on the newest chipsets.
So 2 vertex's wouldn't be limited, but they also wouldn't be altogether that much faster than a single vertex, check some game loading bencmarks, a Intel G1, a Vertex, a Crucial and Raptor all gave load times in most games within a second or two of each other.
THe problem is loading a level ISN'T about the data load only, textures are being read then decompressed, stored and moved, ai is being loaded then essentially put into motion. THe data might load faster but if its still taking the cpu as long as it needs to do its thing, you're limited elsewhere.
Sata 3 really won't bring instance performance benefits, though to a degree as memory gets smaller and cheaper and produced in larger quantities, well, consider a 500gb ssd with a new controller with 5 times as many channels so it can read and write hugely faster.
But the main thing here is, a southbridge with 4 sata 2 ports will "aim" to be able to cope with 1200mb/s throughput, theoretically they can, in reality, they can't. There was no need for a chipset that can do that much in reality because 99.99999% of users won't ever max out more than a single drive at a time so really wouldn't be pushing more than 100mb/s sustained for any length of time. Its just a waste of money, silicone and time making a better chipset.
However a chipset designed for the future needs of using 6 sata 3 ports. We won't be maxing them either, but even a conservative outlook in terms of chipset design, they'll be upping the realistic limit of the chipset to cope with the possibility of newer/faster drives.
No, we don't need sata 3, yes we do want chipsets with more capacity, the way it works is it all comes in together in one neat package. The fact is, sata 3 won't make anything more expensive than if it was branded sata 2.
Sata 2 mobo's didn't carry a price premium, same way as USB port numbers increased we didn't get charged extra, its just a very basic thing.
THen theres the other angle, while a game isn't loading faster TODAY, in two years it could be making a significant difference, maybe in 6 months, who knows. Goalposts move and theres no downside to sata 3 being introduced, sata 2 gave us nothing either in reality, 150mb/s really wouldn't limit "most" of what we do. A Vertex can read faster than sata 1, but 98% of your real usage, loading games, surfing, loading windows, is done in the random read/writes at the lower end of the scale that frankly, Sata 1 wouldn't make a difference to either.
