My power profile explains why I suck at crits and do well in TT's.
I think it is good for getting a general sense of individual strengths and weaknesses. However, I don't think it's entirely accurate in all cases. I have a friend who is a CAT1 and does well in big NRC races and according to this chart he'd be a CAT3. I also know some guys who have CAT1/2 numbers for FTP, but are having trouble getting out of the CAT4. Some of that may be strategy/tactics. However in one case, I know the guy has such a weak sprint which can be problematic in the lower categories where things tend to end in a bunch sprint...
I also wonder about the numbers themselves. I've seen several variations on this chart all with slightly different numbers. When I talked to Hunter Allen last fall, he was saying something about some power testing he was doing on some BMX riders. Guys that were able to generate huge wattages for peak and 5" power. It was enough that he said he may revise his charts again...