Oh, it surely is, but I'm paying a premium for two things:

Additional internal storage – very important if you want one and only one Mac.

Double the RAM ceiling - 8 GB on the MBP versus 4 on the Air. And the MBP is user-upgradable, which feels better to me.

You also get longer battery life with the Pro, but since I'm not usually that far from an outlet, it's not a big deal. I'm also happier to have an incrementally faster and later-generation processor, since that'll hopefully grant a further 6 to 18 months usable lifespan for the machine.

Sigh, makes me regret my setup even more, price-wise. I have a big early adopter problem. First SSD was $680 for 80GB, it died, Intel sent me a second generation replacement. Then I purchased a second for $400, put them in my 17-inch MBP (older core 2 duo) in RAID 0 via an optibay. Then upgraded to 8GB of RAM when I started using redis locally. System screams but the SSDs are showing their age. I almost always run the drives close to maxed out storage. I used to have large volumes like iTunes on my Time Capsule but whenever I wanted to play a song it would take 10 seconds for the Time Capsule to spin up the drive.

http://paulstamatiou.com/ssd-raid-performance-9-months-later

I'm waiting until Lion comes out for any more hardware changes. Now that I'm using Jekyll locally (and will be just rsyncing the files) and it needs to regenerate 1000+ posts with layout etc changes, the core 2 duo is showing its age. And I have LSI disabled..

RAID-0 after having one die? RAID-1 would still get you double read speeds in the cases that tend to matter (small scattered reads), right? And is there a use-case for double write speeds on a non-server machine?

raid-1 may or may not get you double read speeds - it depends on how things are set up. ARe you sure the OSX implementation will take advantage of this?