I would like to understand the limits, advantages/disadvantages of one platform vs the other as specifically relates to CS4/CS5 and/or Lightroom 2/3.
I've done this exercise before.
When you consider only the hardware, a power-packed Windows box is essentially the same as a Mac Pro. Multiple processors with multiple cores, fast bus speeds, multiple internal hard drives, and other features are available on both platforms. If you configure a machine on the Apple Store
and Dell Store
you'll see the prices are almost equal.
The applications from Adobe all function the same on both platforms (I think Adobe called it "parity" back when Photoshop's functionality and features were finally equal on both platforms). You take a series of good photos and process them through either platform and the photos will still look good. Now that Adobe is porting their Mac programs to 64-bit, there is no inherent advantage to either platform. And, I for one, believe 64-bit functionality is moot when working with 100MB-500MB image files (I could've used it with 1GB-2GB scans from 8x10 film, though).
This means it boils down to the OS. And this is where people get opinionated because we get so accustomed to a particular OS and its workflow.
Unfortunately, the only way you'll learn the Mac OS is to buy a machine and spend time using it to see if you are more productive. You can't drive it around the block to know if you'll like it, you'll need to use it for several months before you can make an informed decision. I know a lot of Windows users who have tried and cannot stand the Mac OS. I also know a lot of Windows users who have tried the Mac OS, and would rather die than switch back to Windows.