If burn quality is your main criteria, you might want to give the 4570 a miss. Judging from the preview of the 4570 posted here :
The burn quality on DVD+R media has a few high PIF spikes. Recent NEC drives seem to suffer from this anomaly. While most reviewers choose to ignore it, I think it is quite relevant. The fact is that other writers don't display such artifacts. In particular, the Pioneer 110/A10 series of writers produce burns without such artifacts, despite the fact that they also use NEC chipsets. Note that both NEC and Pioneer writers don't seem to support booktyping for DVD+R discs.
My 4167B doesn't display the problems Arachne listed above and I'm reasonably happy with it. However, I might just be a lucky fellow.
If you are unconfortable with the risks presented by Arachne above and don't really need booktyping/bitsetting, I'd advise you to go for the Pioneer 110 series of writers instead.