True. I think a lot of people impulse bought it but had higher demands and returned them for larger models. I could even see a near future where the 128GB size will become the cheapest model. The smallest size, I'd suggest if you plan to have a versatile twin operating system machine that can run everything and have a low dependence on external USB memory. (Especially if you plan to do Steam-client stuff) However, if you are truly light in use, on both sides of the spectrum, you could get away with a dual operating system 64GB without resorting to externals.
It's what is under the hood that makes it hard for you to stick with just the 64GB. Due to its unusual abilities as a full-blown laptop that exceeds the usual general-use laptop, the temptation to do more with it is astounding. If the capabilities of how it runs things in OSX is impressive, it's just as impressive in Windows and Direct X.
Let me get this straight, this is not a gaming machine (or more so protection so people don't obviously jam such an obvious thing down my throat, even though I know it already) but for a unit as small, it's nearly a somewhat distant 2nd, in small-sized portables to the alienware machine (when activated in gaming mode). Even though it is definitely not *geared* for that, it's hard to ignore how it runs Dead Space, on high details, in native resolution, and manage to look great even if put side-by-side against an Xbox 360 or PS3.
The issue being that 320M, inside there, is a screamer which doesn't look too impressive on paper, but ends up shocking the heck out of you in actual practice. It wont place any records at all, but if you want the smallest and lightest netbook-sized machine likely capable of playing Blizzard's next famed dungeon crawler, when it comes out, (all without choking) you're looking at it. Sure, other machines, geared for gaming, will do better, but they wont disappear between two sheets of paper and still feel like you're just carrying a few sheets of paper, either.
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My take on it is.. The 11" Air is beautiful and brutal. Beautiful because it is designed to be the most elegant and easiest general purpose laptop to carry around and pack away. Brutal because it's also the ultra-portable that taunts capabilities far beyond the general-purpose moniker it's supposed to have. Other laptops with those intended purposes, show their limitations right away and help curb your intentions with their product. This one just makes you want to throw more at it because it seems to beg for it. You'll see.
Right out the box, it's not a heavy-lifting machine...but a (strangely balanced) medium-lifting machine. Almost makes me wonder if Apple accidentally hit on something. The trick is, people can't grasp what medium-lifting is in computer terms, so one will likely experiment to find that happy medium between the two loads. Perhaps the 64GB limitation of it is the main thing helping to root your expectations, unless the temptations take a hold of you and you start connecting USB devices outside the intentions of data transfer and backup. Because the moment you go 128GB or higher, you're probably gonna try to use it in a closer to primary machine status.