Thanks Robotbeat.
I just had a quick look at the Kingston "DataTraveler" range of USB pen drives (just as a example of a decent brand), see below. They don't say if they are either MLC or SLC (but we would would guess cheaper MLC yes?), but do mention different Read/Write speeds (in MB/sec) as either: "Standard", 15/6, 20/10, or 24/10, so not sure sure if that hints at the faster ones would be SLC or just diff. speed MLC's. Any idea if DSS loaded on a faster/slower pen drive would have any effect (once booted)? Cheers.

• Wear-Leveling Technology: Kingston Flash storage devices incorporate controllers utilizing advanced wear-leveling technology, which distributes write cycles across the Flash card. Wear-leveling thus extends the useful life of a Flash memory card (for details, please see Kingston Flash Cell Endurance section, next).
• Flash Cell Endurance: For Multi-Level Cell (MLC) Flash, up to 10,000 write cycles
per physical sector. For Single-Level Cell (SLC) Flash, up to 100,000 write cycles per
physical sector.
According to Toshiba, the inventor of Flash memory: “the 10,000 cycles of MLC NAND is
more than sufficient for a wide range of consumer applications, from storing documents to
digital photos. For example, if a 256-MB MLC NAND Flash-based card can typically store
250 pictures from a 4-megapixel camera (a conservative estimate), its 10,000 write/erase
cycles, combined with wear-leveling algorithms in the controller, will enable the user to
store and/or view approximately 2.5 million pictures within the expected useful life of
the card.”1
For USB Flash drives, Toshiba calculated that a 10,000 write cycle endurance would enable
customers to “completely write and erase the entire contents once per day for 27 years,
well beyond the life of the hardware.”
SLC Flash based-products, typically found in Kingston’s Elite Pro™/Ultimate Flash cards
and DataTraveler II, II Plus – Migo Edition and Secure / Secure – Privacy Edition USB Flash
drives, offer both high performance and high endurance.