They are entirely different internally. The 4167B is pretty much a successor to your 4163B and uses a later evolution of the chipset used by that drive. So like your 4163B, it doesn't do auto-bitsetting either. However, there is third party firmware that will make this drive do auto bitsetting. The catch of course, is that third party firmware invalidates your warranty. If you are the sort of person who uses region free firmware, then this won't matter to you, since it involves pretty much the same thing.
The 4166B uses an entirely different chipset and so has quite different features. It does feature auto-bitsetting out of the box. However, it's a lot more expensive than the 4167B because of the lightscribe feature.
Both drives have pretty good burn quality so it is a case of risk vs price. It's up to you.
On a side note, you are aware that there is a little utility that can be configured on your system so that it automatically does the bitsetting on your 4163B (or even the 4167B) each type you bootup right? This eliminates the need to set the booktype manually and gives the drive a form of auto bitsetting in a sense.