I grabbed a few of the parts hoping to sneak a peak, but it seems the 7-zip format isn't as friendly as rar with respect to partial extractions. It seems to want all the parts present before it will extract anything, unlike unrar.
And while it may use some sort of checksumming internally, the 7-zip program doesn't seem to display any checksums the way unrar does when given the "list contents" option.
My first experience with 7-zip, but so far I'm underwhelmed.