1. Sell the MBP 17.
2. Buy the high end MBP 13 refurb.
3. Buy a optibay from MCE and ditch your optical drive, take your boot HD and throw it in the optibay.
4. Buy a 256GB SSD, make it your boot drive.
5. Buy a 30 inch dell monitor.
Result: 13 inch MPB that's faster than your 17 (due to the SSD). Is super portable and when you need a "workhorse" at home - you've got 30 inches to work with.
Plus, I bet you saved a few bucks.
Oh and the reason I mention this is because I'm about three weeks away from doing it myself.
Are you sure you're really doing this in 3 week? Sounds like a very bad move to me.
I am always amused by the posts comparing performance on the 13" macbook 'pro' and on the real pro models. Sure for processor intensive work you shouldn't notice much difference between the 2.53ghz in the 13" and the 2.66ghz or 2.8ghz in the 17". But do any real pro tasks on it, motion for example, and the difference will be very obvious. The 9600 really is a lot better chip than the integrated 9400m. The 13" is fine for browsing, office, light games, photoshop and ilife level editing (might even stretch to using FCE on it). Do they also still cripple the max ram on the 13" models?
My 17" has a 128gb ssd in it and the speed up in app loading and booting is nice but the write time difference is occasionally noticeable and a slight drawback. It certainly wouldn't turn the 13" into a faster computer than the 17", just faster to load apps.
As far as selling your 17" goes you might expect back about $1500. Conveniently the price of the 13" 2.53. A 256GB ssd you say? well, last time I looked a proper one would cost you over $1000, but a crap brand one for $800 will do. Then your 30" dell monitor is currently $1700. So extra expenses of $2500 to still only have one computer, that is slower than you started with and a big external monitor. Not the best deal in my opinion. Did you also mention an optibay? They're not cheap either.
So unless you like slower computers and don't like money. I would suggest not doing that.
As for the OP, I would recommend the MBA. I had a rev.A and it was terrible. But.. I would get a new one that works properly as I really did love it even with it's problems.
Stu