I've personally used 3 different card readers from R4. My blue case/blue led. my son's blue case/green led. and my son's friend's new black case/green led. No problems with any of them. I wonder how many people use the "safely remove hardware" button to disconnect. The reason I wonder is because I've always just yanked most USB devices(XGFlash 256, Mp3 player, mouse, printer, etc.) with no ill effects. My card reader is the only device I use the button for. Just something about that little blue light being on that makes me safely remove hardware everytime. I have on occasion had my computer freeze up when inserting the reader, but never to the point of having to reboot. It either fixes itself or I just unplug my hub and replace, problem fixed.
EDIT: also the only corruption I've experienced was while using DSFTP. It corrupted some files I uploaded into sub directories. All stuff uploaded to the root is fine, but DSFTP seems to have problems with sub directories for some reason. I formated and everything is fine. I don't use DSFTP anymore.
Without fail, I never use the disconnect hardware button when I remove my USB adapter. With no ill effects.