Yep, that would not come as a suprise - what you are looking at are a disc's 'correctable' error levels, all discs have errors on them that the drive's error correction compensates for. But if they become concentrated enough in one spot, they will create reading errors/problems. About the first 300-400MB of your scan shows very high error and jitter levels. In your burns that will play about 3/4ths of the way through, I suspect that you'll find high levels towards the outer edge of the discs. BTW, although your TRT of your second disc looks ok at the beginning, that's probably because burners are better readers than standalone players, plus the fact that the read speed is much slower at the start of a disc so it's not as hard to read at slower speeds.
So what does this mean then you're probably wondering - like I said in your initial tests, while the error levels are a little high, they're not horrible, and the TRT (transfer rate test) is perfect. If you are getting bad burns with these discs in your Benq at 8x, it's very likely that you just got a bad batch of discs. This is under the assumption that the discs are not physically being stored poorly, do not have heavy scratches/fingerprints/etc., and that the discs do not have adhesive labels attached to them (full size disc labels often cause problems).
I would suggest trying some other discs to see how they do - Verbatim's discs are very good and often on sale, although the Benq 1655 is a good enough drive that it can handle almost any decent media just fine so it doesn't necessarily have to be great media to confirm whether or not the drive is having any problems, though I don't think your problem is drive related, much more likely media related I'm thinking.