I've been using a SanDisk compact flash reader (USB interface) for a few months with OS X and it works fine. I got it for about US$20 from Amazon.com.
All my image transfers have been great. My only "problem" has been the way X ejects the disk. If you drag the disk to the trash, it will eject it, but if you don't remove the card immediately from the reader it will remount the disk. Not a big deal, just a minor quibble....
Q