I had a SSD (32GB MLC PATA) in my PowerBook G4 12", and it wasn't THAT big of an improvement over the stock 4200rpm drive. The differences that I noticed were the faster app launch time and system boot time. The sustained write-time, esp. for an MLC drive like one in air, makes the SSD's overall performance boost negligible for my needs (because i need to move large files to and from my external storage, 120GB really isn't enough by any means).
There was no significant improvements in terms of overall heat and battery life, and I always thought my SSD was more of a bragging right that I had.
I have used both rev B with and without SSD, and the differences are night and day. Anyone who has used both can tell you how dramatic the differences are. I used to tell people rev B with HDD is ok, and it is, but for a secondary Mac.
I opted for a uMB over low end rev B MBA when my MBA rev B w/SSD was stolen a month ago. I am waiting for a rev C MBA, and didn't see the sense in buying seven month old tech for full $2499! And I used a friend's rev B w/HDD for an afternoon. It was incredibly different than my SSD. It wasn't fun. It couldn't do everything in a snap. The uMB is much faster than the low end rev B MBA. As much as I love the MBA, it just loses its lustre instantly with an HDD. It sucks to say it, but it's true. I am a huge rev B MBA fan, but my excitement comes from an incredibly small Mac that travels excellently, looks amazing, has a gorgeous display, and is superbly capable/fast with SSD (it truly feels like a Mac Pro when doing simple tasks while hooked up to a 24" LED ACD).
Unfortunately, when buying the low end MBA, the odds of getting the line ruined display are much greater. So too slow and potentially problematic display made me more willing to settle with a uMB while waiting until June to see if the MBA gets an update. I guess it just seems like a terrible time to buy any rev B MBA. Really, if the price was knocked down by a bunch it could become a decent value.
And to the Air Force EXPERT, the 4200rpm doesn't just boot slower and open apps slower, the differences can be seen instantly and are really dramatic.
Also, you cannot compare a 32 GB SSD as not being that much faster than the SSD is in the rev B MBA. SSDs are incredibly different. Not only that PATA can limit throughput depending on speed. If I were you, I wouldn't assume that your experience with SSD applies, because it doesn't. The bottom line is the SSD in the rev B MBA reads over ten times faster. It's SATA-II not PATA, and it's a really nice Samsung SSD.
No matter what you do, you should hold out to see if the MBA rev C is released before or after WWDC in June. It could get a lot of improvements. The low end will probably get a bump to 1.86 GHz CPU, may get new battery tech, may get more RAM, may get a 128 GB SSD, and will definitely get a superior line-free display. Even if the differences aren't as drastic as I have suggested, you may get the rev B SSD on clearance for nearly the same price as current low end costs.
At the end of a product cycle, right before a refresh, a Mac is a terrible buy. You are getting 7.5 month tech for full price which makes no sense. Buying prior generation or new generation makes the most sense right after refresh.
Good luck.
