Hi. I may have missed this part of the discussion but what significance is the lower speed 1.3 GHz processor? Forgive my ignorance but while they have given us a chip upgrade doesn't this slower speed negate a lot of the benefits?
I've been hoping WWDC would help me decide between a MBA plus external monitor and the 21.5" iMac but I am still not sure what to do. An upgraded monitor would have swayed me (even if it was just HD). I'm now wondering if I should reconsider and just get another PC ultrabook. I was thinking of moving over to Mac but now I'm less sure. Some of the PC ultrabooks have a HD or better screen and there are none of those compatibility issues with external monitors.
Just FYI, trying to measure performance in the GHz number alone has been . . . problematic (and a point of a lot of discussion) for some time now. Quite simply, if you want to measure relatively performance for a CPU within a given family of CPUs (say, the current Intel Haswell line for Ultrabooks), using the GHz number alone may be enough information to make a valid comparison. Even that, though, is not the total answer (there is something called cpu cache which can greatly factor in, depending on the applications you run). The further you get away form that cpu family (say last year's model; or two years ago; or an entirely different product line (server line, let's say) or a different manufacturer (AMD or ARM) and it becomes really, really difficult. Sorry if this is pendatic or a little obvious, but I am just guessing at your level of knowledge/ignorance. An imperfect analogy might be trying to measure the "performance" of two automobiles by measuring only the horsepower numbers. But to give you a good answer, you really need to know the rpm level at which those horespower numbers or measure, you need to know the torque generated at what level, you need to know about your transmission, you need to know about your suspension . . .
What might be a better thing to ask is "How quickly can this model do X?" like does this sample workload (encode a movie, or play this game, or whatever) compared to last year's model? Even then, the platform upgrades (SSD upgrades, chipset upgrades, OS upgrades (when they drop Mavericks, which I assume they were testing with but will not release with the new hardware right away) may have something to say about how fast any given load happens. I have access to a base 11" 2012 model (with the only exception to base being the 128GB SSD option). I am hoping to go visit the Apple store in the next couple of days, and run some tests. I am not sure how much they will allow me to do/load, but if you are interested in anything in particular, let me know. People like Anand (anandtech.com) will probably do a much more intensive comparison than I would/could do, so you can also watch for those kinds of updates. Many testers will add things to their tests if you ask them nicely in the comments sections on their postings, and it does not take too much more time.
Given what I have seen from previous chips in this category, what I have seen from a recently released model of a similar Haswell chip, and given what Apple said today about OS X Mavericks, I would guess that this chip (even the lower end i5 model let alone the higher end i7 model) would be ample cpu power for most people for most of the time. It really would.
Given the relative cheapness of quad core cpus (at least in the desktop and server worlds), I personally would like not to buy anything new that does not have at least four physical cores. It just gives me a lot of flexibility for workloads (encoding, lots of background tasks, virtualization, etc). But the simple fact is that the great majority of people are not using their Airs for this purpose. Four threads over two physical cores with an elegant OS seems responsive enough for the majority of people's current workloads, I believe.