Thank you for the reply, for starters, what is your MBA's configuration? Also when you say that I would not notice any slow down in PHPstorm could you break that down a little more, because I'm using Webstorm now and thinking of going to IntelliJ. Battery life is important, and the people in your office that are using the rMBP on battery do not have the timeframe that the MBA does.
I have the i7, 8GB and 256GB SSD. Even with an edu discount the 512 would have put it above 2K and I needed to save some beanies. You need the RAM, and my researched showed some possible lag or freezes with the i5 CPU. The max turbo is also a noticeable difference between the 2, I would not consider the i5 or 4GB to be workable, especially if you're keeping it 2-4 years.
IntelliJ is used for Java/Scala/NodeJS development, Web & PHPStorm are for PHP isn stuffs, completely different footprint when you're actually running.
For basic editing there are no slow down in editing mode, the problem with any jet brains IDE is they're java base and start having problems when your project get larger. For example, Rubymine has to keep all of Rails and any associated gem source code and your project's code in index for code auto completion, that can get to be around 400K+ lines, and the indexing process is longer and autocomplete more jerky unless you've raised the delay a little bit (I use 0.5 second). PHPStorm projects are much smaller and usually snappier for things like auto complete. In any IDE I've used, I would consider them all to be very responsive during editing, no lag or freezing that are noticeable.
The slow part for Jetbrains IDE is during project indexing, that still take a little while, but a very acceptable amount of time on the i7 and SSD.
The only time you will notice any lag at all is when starting IOS simulator in Xcode, that take a couple of seconds, not like 7-10 like on my old MBP, but still like 2-5 and it's a delay you'll notice.
I went to the apple store last night and once again explained my situation, the result was either the maxed out MBA I7 512HD 8GB Ram, or a 13" rMBP or 15" rMBP. I was also told that the i7 was an overkill for my current needs and that the I5 would be fine with 8gig of memory out of which is special order or BTO. I mentioned that the MBA would probably be getting a retina and that was shot down because of the battery life. On the MBA the screen was fine although a 15 inch would be the better, just can't believe that Apple does not have a 15" MBA, although if I buy the 13" then it's a no brainer that this summer there is going to be a release of a 15". Was going to bring one home and try it out this weekend but figured I'd sleep on it some more. Over all they said just return what your not happy with.
The i7 is not overkill. Apple uses different vendors for the SSDs, at 256GB and 512GB it's Samsung (the good one). The weight difference between the rMBP and MBA is incredibly small, 0.5 lbs. The choice is yours based on your screen need, budget, and if you need that extra 8GB. The real choice is the battery life.
There will not be a rMBA because if you look at the rMBP, it's not really thicker by that much, the problem is the battery doesn't fit the MBA, that's why they called it the MBP. The difference in the 2 as a design compromise is really the battery, I got 6+ hours doing some heavy stuff before 10.9, now, I can probably get 8-10 hours in a real life developer usage mode.
If battery & budget isn't an issue, go for a rMBP. If it is, I think a maxed out MBA will serve you just fine until 2017. Just don't be one of those people with 3 browsers that has 20 tabs each opened while you're trying to use PHPStorm on a massive project that's connected to a 20GB InnoDB backend running with MySQL hogging 4GB on the same machine...
