I will go against the grain here...personally I think the Raptors are definitely worth using.
Access times still beat all the new 7200RPM drives - thats what makes your system feel more responsive. I use two older 74gb raptors in my rig, one for XP-64, the other for windows 7 and I must say I'm very pleased with the performance.
I like them more than my seagate 7200.11 640gb hard drive to be honest.
I will make an analogy: The raptors are like a car thats geared really low and can hit it off the line super fast, but top out quick. The fastest 32mb cache drives are geared medium-medium/high and can do decent off the line, but have a high top end. Now are you gonna be driving around in New York, racing stoplight to stoplight? Or are you gonna be on open highway most of the time where you can open up your top end to the max?
I expect the city driving to happen around 80% of the time - unless you're always copying and editing gigantic files you wont notice a difference.
That's my opinion at least, others might have a better argument for going the other way.