While the ultimate bandwidth of standard PATA (and there are several flavors but the MBA features about 100mbps) is less than SATA (again several flavors but the MBA version tops out at about 3gbps), no current 1.8" 5mm form factor HD or MLC SSD is able to exceed either transfer speed so the interface is not the limiting factor.
There are a lot of folks that just assume a newer technology is better or because its theoretical limits are higher its better. Design and integration often have a lot more to do with it than the theoretical spec of the parts used. Those same people are the ones that think because the "specs" of a $600 PC are better than those of a $1200 PC that the $600 PC will be faster and better and the $1200 PC is just a waste of money.
There are many factors other than SATA/PATA that ultimately determine a particular drives maximum throughput in a particular machine. They include drive design, particular chipsets and thier interactions, machine design, memory speed, and cpu horsepower among many.
In the case of the MBA revA vs revB you have chipset differences, hd design and density differences, SSD design and density differences, memory speed differences, and CPU differences. The rebB is simply a much quicker machine even if you were to put the same spec HD or SSD in either.
Talking HDD, the revb drive is slightly faster and the revB is a LOT faster so they combine to make a significant difference in real world performance. PATA or SATA you are never going to get great performance out of a 4200rpm single platter drive though.
The SSD differences are much more significant to the revB drive being a generation ahead in both read and write speeds as well as density (nothing to do with SATA or PATA as the drive read/write speeds are still less than the PATA limits). That combined with the revB power and speed make a huge difference.
So all you hardware freaks
out there that want the latest and greatest technology instantly released in a new machine, keep in mind that design and integration of components often has a lot more to do with a machines utimate performance than the theoretical spec of its parts. Careful design and integration takes time which is why you see the release cycles on apple products that you do, its also why apple products tend to stand up ofer time better.