Like I said, they're doing their "disk" performance testing with a large RAM-based disk cache enabled in the computer. That doesn't measure the speed of the drive, it measures the speed of RAM and software. It's not unreasonable, since RAM disk cache is fairly standard, but it's cheating with regard to rating the performance of the disk.
The true performance of a disk is measured with a setup that exercises the disk, not memory. Modern disks have internal cache in the drive, but it's typically 64MB or less, not 500MB or 1GB like a RAM-based disk cache can have.
The reason that difference matters is that if you're running a lot of programs concurrently, you can't allocate lots of RAM to the RAM-based disk cache, or else you end up swapping running tasks to disk, in which case you're even worse off than before.
You can spend another $40-80 on more RAM (assuming your mobo can hold it) but then you've lost the cost advantage of the "cheap disk".
Lesson: There is no such thing as a free lunch.
I won’t argue with you 7200rpm is better. In the real world most computer users won’t know or see the difference between 5400 and 7200 because their computers run slow for other reasons. Such as not reloading an OS for years and years. Or like my nephew who called complaining about slow internet at college. Turns out he had not rebooted his laptop for weeks..... So Firefox had turned into a memory hog. I showed him how to just reboot Firefox and that solved the problem. But how many other operate like this for years?