The MBA is not snappier than the rMBP and never will be. Get what you want but don't listen to nonsense. rMBP has a smaller footprint and the weight difference is only noticeable if you have the arms of a 2 year old child. The battery life of the two is also very similar. I get about 11:30 out of my rMBP and about 12:20 out of my air.
To all of you who are reading this thread - trust me, even my old 2011 MacBook Air was snappier than my brand new rMBP for most usual day-to-day tasks! So yes, the other posters in this thread are correct. Oh and I'm very interested in how you're getting 11:30h out of your rMBP. I haven't been able to get more than 9h, tops! (not that that's bad or anything..) Screen at 50 % brightness, BT always off, Wi-Fi on.
Here's a review I posted in another thread while answering someone's questions regarding the transition from the MBA to the rMBP:
I am in your same exact shoes going from a 2011 MBA 13" 4GB/i5 and was thinking about going to the 13 Retina Pro with 8GB
How are you liking the machine so far?
Is it speedy enough? Any issue with loud fan, image retention, websites not showing up as retina / blurry?
Do you prefer the MBA over the Pro?
Is the screen really that much better?
I've now used my rMBP for a couple of weeks, and as I still had my MBA around for a while before selling it, I was able to compare the two back to back as well.
Here's the thing: The screen really is THAT MUCH better. Nothing else I've used can compare. Everything is crystal clear, making it a joy to use for reading, writing, watching/editing photos, movies et.c. The MBA feels quite bad in comparison. However, you must know that this comes at a price.
The MBA was smoother for browsing the internet, smoother for scrolling documents, texts, and so on. When you scroll through pages, there is a tiny bit of lag on the rMBP, and this computer has way better specs than my old 2011 MBA. Some internet-pages are worse than others. MacRumors works well, but pages with plenty of flash or ads do lag, and it hurts to say it. There is lag even in the "Best for display"-resolution, but even more so when you use scaled resolutions. Sure, the rMBP will definitely have more power than the MBA, but if you just use it for daily tasks, such as web-browsing, Office, email, music, movies et.c., I think the MBA will feel faster. However, the latest OS X update, 10.9.3 did reduce the lag to an extent, but it's still present. Sure, the rMBP is definitely speedy enough, leaving my 2011 iMac in dust - but the MBA felt a bit snappier in day-to-day use.
To be honest, I was SICK of the MBA-screen. The problem was not only the resolution, it was something else which I can't really put my finger on, but I got really annoyed after reading on it for a while. Heck, even my old 2007 1280*800 MacBook was more comfortable to read on. The rMBP took care of that problem. Moreover, I get even better battery life out of the rMBP than my old MBA. The rMBP is as cool as the MBA, and whereas the fans used to kick in at times with the old MBA - I've never even heard them spin up on this new rMBP - it's dead silent. The rMBP also feels like a much more high-quality device.
Here's the thing. I'm always interested in adapting new tech, and I've been interested in the rMBP since it was released. I do feel like a bit of an early-adopter with this rMBP, as I think the experience is not perfectly mature yet.
For me, it was worth the upgrade as I was out of warranty and got a great price for my old MBA, while also buying this rMBP at 10 % off. I was not going to replace my old MBA with a 2013/2014 MBA as it's more or less the same thing, except for improved battery life, so the rMBP was the logical choice. Last but not least, the rMBP feels a lot more high-quality than the old MBA.
I'm sure most of the lag-issues will be worked out when Apple releases 10.10, or when all web-pages are retina-ready. Other than that I'm perfectly happy with it. No image-retention, no loud fans, et.c.
TL;DR: The question you need to ask yourself is how much you care about that amazing retina screen? The MBA is cheaper, snappier (for now) and has better battery-life. However you should know that the MBA also feels a lot cheaper than the rMBP. You should also know that for more intensive work, the rMBP definitely is a faster computer, which will start to show with time, as more software/webpages are getting optimized for it.
Edit: I'm sure I'm cursing in the church by posting this here of all places, but this is my experience of the transition from the MBA to the rMBP. While it's an amazing computer, it isn't without faults.
