The sole plate was not fitted correctly. After a few minutes of use the front of the sole became detached and blew the house fuse. The item has been returned for a refund. I will be looking for a different brand.
I use it with the Komputerbay SD / SDHC / MMC Card to Compact Flash Type II High Speed Adapter and it works very well. Up to now I've had no missed downloads. However, I've only used it at close range, e.g. < 10 feet which is all I need it for. After all the negative reports of its use with the 40D I'm happy.