Thanks for the advices.
I took my wife to the local Apple store to test drive both 11" and 13". She said she'd be very happy with the 13". I am going to get her the 13" i5/4GB/256GB. I believe it's going to be a very good machine for learning Photoshop, Lightroom, and web design...
I am also going to take this opportunity to replace my late 2008 with something more up to date 😀. I am torn between the upcoming Haswell 13" rMBP and 13" MBA i7/8GB/256GB. I'll be using it mainly for programming in Java, and learning Python/Ruby/Node/Android/iOS. I have two issues with retina:
1) I have an external Dell Ultrasharp 24" IPS display and I want to use it whenever I can since it provides more screen real estates.
2) The rMBP will likely use more CPU and GPU cycles to drive those 4M retina pixels. Does it mean that performance wise, the MBA and rMBP will have similar performance?
Unlikely. If we're talking about raw CPU performance an upgraded current 13" rMBP already beats an upgraded Air. The difference is largely a matter of battery life; the Air will beat that upgraded 13" rMBP by some huge amount as far as battery life.
The GPU concerns you mention could come into play to some degree in the current 13" rMBP (because of TDP limits the CPU can sometimes get throttled if the iGPU starts to use too much power, which might happen because the HD 4000 is massively underpowered for that resolution).
With the new 13" running an HD 5100 I would expect this issue to largely be gone. The iGPU should be able to perform any "normal" tasks without cutting into the CPU's power supply, so under most conditions the CPU will be able to run up to its turbo frequency and should outperform the Air's i7 (assuming we're still talking about an upgraded 13" rMBP). Obviously 3D graphics are going to be an exception, since rendering at the native retina resolution can easily overwhelm any laptop GPU (even a 780M isn't going to like it).
The question is mostly about battery at that point. Haswell is going to improve battery life, but likely not as much as it did for the Air. No matter how efficient these new CPUs are it's going to take more power to handle the higher resolution and run those faster CPUs, even at light load.
I picked up an Air this week for the amazing battery life, but I have to admit that taking it back and waiting for the Haswell 13" rMBP is very tempting. It's an amazing machine -- fast and with ~9 hours of real world battery life (i7 version) -- but it's hard for me to go back to TN panels after using IPS for so long. If Haswell can significantly improve the rMBP battery life it might be a better choice for me, as the battery life I'm getting from the Air is actually overkill for my usage.
This is getting kind of off topic, but I'll mention that my main issue with retina is how it's handled at the software level. I don't like the idea that I can't control system display resolution manually, instead being limited to a few types of scaling. If I want to set the display to half resolution (1280x800) and use 1->4 pixel mapping I should be allowed to do that (maybe there are 3rd party utilities to solve this by now, I don't know because I don't have a retina MBP yet). This mode would solve two issues at once: It would improve performance of windowed 3D rendering (for example, in 3D graphics software) and reduce the impact of retina on day to day battery life while still allowing me to have that amazing IPS panel.
