Having played with both the 6S and 7S, I feel pretty comfortable that both are reporting errors more or less the same way. What is true is that every drive has it's preferences for what media (and burn speed) it "likes" to read. Here's an illustration, the same 2 discs that were burned in the 7S, now scanned in the 6S:
As you can see, the 6S reads the Verbatim disc in much the same way as the 7S, but the TY is very different. thus, the 6S prefers reading TY media. But the 7S treats them the same way. If the error reporting was different in the 2 drives, both discs would vary by the same amount when scanned in the different drives.