Ok, because of this post I had to try a Intel SSD. So I bought this one here. I moved all my data over like this. It all worked well and now I am running on my new SSD. And there is a big difference. So a quote from here is totally true:
If you’re curious, it’s the random write performance that you’re most likely to notice and that’s where a good SSD can really shine; you write 4KB files far more often than you do 2MB files while using your machine.
Also Startup-Time of your computer is crazy fast! I can hardly see my Gentoo-Message while BootUp anymore. If your are on Linux, also consider these options for fstab and booutup: noatime, elevator=noop. But read more of your own in the above mentioned links.
Update: There is a newer, faster and cheaper version out now: X25-M G2