As far as I can tell the update has only affected GC homebrew created using 'mkisofs' with the El Torito switch. Naturally the Wiikey and Wiifre config discs won't work. I have not checked but I am certain that new images are available. I have tested throughly and have not run across any bricked modded consoles from the update, nor have I noticed any wii backups being unplayable after the update.
As for drive speeds, I have found no evidence of firmware updates on DMS or D2B drives. From what I can tell the average drive speed without using wii OS is 968-1,023 KB/s. I don't see the wii os doing drive speed checks, as I can't see the drives achieving speeds much higher than 8x 1,200 KB/s.
I'm surprised they warn you, that's nice of them, lol.
Nintendo really doesn't care too much about piracy. The R4DS is very popular and Nintendo hasn't done one thing to stop it even though they easily could.
Personally speaking, I know for a fact they care very much about this. Sites found hosting wii images and even ROMS will be receiving letters from Nintendo's lawyers. One bad thing about the VC is that it is reviving old copyrights. In short, Nintendo does very much care about piracy. You will be seeing products like these and wii chips being removed from all major North American resellers.