Michael,
Thanks for the revealing review of the new Sandisk cards. I doubt you have been able to test for this, but nonetheless possibly something potential customers may need to consider - could there be backward compatibility issues with various previous generation cameras? I ask because I seem to recall (without remembering the time or the details, so this is fuzzy) that a previous version of an up-graded CF card did not perform well in certain cameras. Hence just for example, if I were to buy an Extreme 4 for my Canon 1Ds (original model now dated over 5 years), could I be facing issues?