Your synthetic benchmarks will look wonderful, but you will not be able to tell the difference with actual work.
I tried it with 2 X25-M 80gb ssd's. A single 160gb ssd worked just as well.
If you need more space, go ahead and get a second one, or sell the old and get a larger one.
There may eventually be a big disadvantage as the drive fills up, and the lack of trim slows down updates to a crawl.