Two points: Firstly it may not be fair to benchmark a short stroked Barracuda to a normal Raptor; because the benchmark will not specify the portion of disk that is being tested, i.e. the inside or outside. A short stroked Raptor may perform, depending on the test, better than a normal Raptor.
Secondly, It is not necessary to sacrifice the disk space, to short stroke a disk. You could use a disk management tool to create a 100GB partition for apps and OS, and another partition for data; using a normal windows format will probably do this, but a proper tool will ensure that you use the correct blocks.
The reasoning is that you will most likely not be accessing your data disk when you boot, or play games, so performance here will be improved; and you still have all your space....