Yes, I was mostly concerned about the maximum drive size.
I've seen one claim (not well documented) that the 4G/Photo/Color won't recognize anything above 60GB. Unfortunately, most of the articles detailing this upgrade date to when 32GB was a huge upgrade, so there seems to be little information about the older Classics and "big" drives (unlike the 7th Gen Classic which as been upgraded to 1 TB).
Thanks for the links.