TRANSFER RATES- FLASH DRIVE SPEEDS- Which models do what????

Seems to be a recurring theme on here of people questioning the speed of there flash drives. A client of mine uses a Sandisk Cruzer Edge of Ready Boost in Vista, as others wont work. So does that mean any Cruzer edge will work. How are customers supposed to work out which Flash drive had the correct speed. Sandisk do not seem to let us know anymore. Or is there a correlation between models? Who knows as I can’t find the specs of flash drives easily anymore,

The device must be able to do 3.5 MB/s for 4 KB random reads uniformly across the entire device and 2.5 MB/s for 512 KB random writes uniformly across the device.

Which flashdrives will meet these specifications? Is there any why to find out when I buy a Sandisk flash drive what the transfer rate is. Without emptying my pockets buying titanium top of the range drives?

Thanks for your help guys:confounded:

from what i understand sandisk does not test for readycache compatiblity any longer. also they only have one performance related drive currently which is the Cruzer USB 3.0 drive SDCZ80. Others may be hit or miss as to working with readycache.