Metroid -

I'd still ask Tony, but from what I remember the Vertex 2 was initially going to be SF-1500 based, but OCZ realized that it was going to be cost prohibitive to launch a consumer drive based on that chip.

The reason for the Vertex LE is simply that OCZ must have gotten a good price on the first batch of SF-1500's and decided to build an exclusive, limited edition product, in order to recoup their investment.

Unfortunately, I don't have any true sources to link to, this is just info I've gathered by perusing the OCZ forums over the last few months. I'm sure Tony will be able to give you a much better answer