Let's first analyze this by ignoring the PO Failures, since they represent a major anomaly.
I too use Ritek R03's and I too saw similar improvements in the scan when I went to B7T9. In particular, your average "PI Errors" has been cut in half - from 27.05 to 12.87. Similarly your PIE total went down from 393,162 to 169,152. Your PIF's are slightly better and this is reflected in your quality score of 97% versus 96%. And your jitter is also a bit better with B7T9. In particular, the max jitter is reduced from 13.3% to 10.2%.
So there is little doubt that B7T9 is the better firmware for this media.
Both scans look to be very good scans, and are similar to what I get with my Ritel R03's (but without the PO Failures). Those PO Failures should NOT be counting! They are COMPLETELY out of character for that type of scan.
If you have time, there are a few additional tests I'd like to see done:
Rescan the disc at 4X and save the results
Then rescan it at 16X and save the results.
Finally, use CDSpeed to do a surface scan of the disc. To do this, click menu item "Extra->Scandisc..." to bring up the Scandisc dialog box. Next, check the "Surface Scan" box near the lower-left corner, and click "Start" to do the scan. This will do a sector-by-sector surface scan of your disc, and show the results graphically by lighting a green box for each good sector. The boxes MUST all be green; if you get a red one, you truly have a bad disc. If the scan is all green then your disc is good and the "PO Failures" count is quite possibly bogus.
Post all three results to this thread so we can see them.
There was a claim made recently in the NEC forum stating that the BenQ "PO Failures" count is not reporting reliably. http://club.cdfreaks.com/showpost.php?p=834642&postcount=501 But this was with respect to -R media, and you're using +R media so I don't know if it is related or not.
Since this situation is unusual, it would be interesting to scan this disc on another system equipped with either a BenQ 1620 or with a LiteOn burner, just to get another opinion.
Here are a couple of other things to consider:
IDE Drivers: Try and use only the Microsoft ones. NVidia, Via, and even Intel IDE drivers have been known to cause all kinds of problems with respect to DVD writing.
Your IDE cable: It should be a flat 80 conductor cable rather than an older flat 40 conductor cable. You should generally try and avoid round IDE cables, unless you are certain that you have a good one.