Yes and no. It's not correct to compare the G2 which is running 2.2 and the Vibrant which is running 2.1.
But it's also incorrect to say a lag fixed Vibrant is faster.
When you look at the Quadrant Advance scores, you'll see the boost on the Vibrant is all from the I/O score. That's why a lot of people call the lag fix cheating.
Whereas the score on the G2 is higher than 2.1 phones because of both the CPU score due to the JIT compiler and also because it looks like the G2 has a nice I/O score.
Comparing the overall score on Quadrant is pretty pointless, but if you break down what the scores mean, you can see some insight as to what is actually happening and how the scores really compare.
It'd be more accurate to say that a lag fixed Vibrant has a better I/O score than the G2 which leads to a better overall score.
The CPU side of things is not really compareable until the Vibrant gets 2.2. Even then, Quandrant has optimizations designed for Snapdragon CPU's. So the Galaxy S and anything running an OMAP (Droid X, Droid 2, etc) processor may remain at a disadvantage with the CPU test even with 2.2 installed.
PS: I an running a Vibrant with Bionix 1.6 with Voodoo lagfix. I can tell you from experience than an optimized rom like Bionix and the Voodoo lagfix may score lower on Quadrant, but it is noticeably smoother in everyday use than the older, ext 2/3/4 lag fixes. The older lag fixs essentially create a buffer for the file system which bypasses the journaling system builtin Samsung's proprietary RFS file system (Fat 32 plus journalling). The buffer determines what changes really do need to be written to the file sytem and only then writes it to the internal memory. With journalling out of the way, the I/O score gets a boost. With that approach, the phone is succeptable to corruption and has some wake up lag with certain implementions.
With the voodoo lag fix, the RFS file system is completely replaced by a linux ext 4 file system. I consider this a more permanent solution. No buffering required, no external memory or internal memory partitioning is required.