I believe Dell uses Samsung as their SSD OEM. The 470 and 830 series.
Sounds like it could be like the Samsung 830's.
The specs dell gave me was:
Read specs- up to 500 mega bytes per sec
Write specs- up to 320 mega bytes per sec
These specs are not exactly the same as the 830's, but dell did say they may have various vendors and they could change depending on procurement plans... plus they said they sometimes request drives to their specific specs. Either way it seems close to the samsung.
I just know if I look at the price even AFTER our discount the 128GB is still about $100 more than Samsung 830 128GB. And the 256GB is $650 which is about $350 more than Samsung. Perhaps these are considered enterprise class or something or gone through more testing... don't know. I have heard a lot of stories about SSD's leading to BSOD or other strange stuff so maybe these are designed with more stringent quality leading to more cost.
I just can't seem to make myself spend $650 more for a 256GB SATA III SSD when I can get them for $220 for the OCZ Vertex 4.
Greg