Ok, I have been bleating about the speed of SDHC readers and the obsession with USB2. I have a great FW800 CF reader, but despite the 30MB/s cards, 20MB/s seems to be the most we can get out of the current crop of readers.
With a full day's shooting (by 2 cams) I was dreading the time it was going to take to offload to my VR mini... then one of those "why didn't I think of that before" moments... I used two card readers at once.
No problem with dumping two streams to the e-SATA connected VR and even added a FW800 stream from my KiPro. I actually got to bed at a reasonable time :-)

Chas.

Nice to have good sleep

USB2 is good up to about 40MB/s, or two streams at 20MB/s each

most computers have separate usb channels though, so you can get 40MB/s per port