The 3ware 9500S controller is an outdated, antiquated piece of tech by todays standards, I wouldnt recommend them to anyone at this point.
The max read speeds you can expect from a 9500S is around 420-430MB/s in raid5, and that is with 11-12 drives, not 4 or 3... As for write speeds? I managed 130-135MB/s write on 11x1TB with heavy tweaking on linux, so 30-40MB/s to a 3-4 drive array sounds about right. i've seen benchmarks citing close to 200MB/s for raid0 write, but you'd be hard pressed to manage that in a production enviroment.
If you want good performance without scrapping the old arrays, I'd recommend getting a used 3ware 9650SE-8 port card off ebay. These cards have a PCI-E 8x interface, and performance is in a different league compared to the 9500-series