i guess its a little too late for the advice, but i would have waited. I know you say its worth it and all but 1) theres no way they will not update the rMBP. Of any laptop apple sells, the rmbp needs the upgraded CPU/GPU the most. There is still moments of lag and processor intensive tasks can still lag the computer.
2) there
might have been a price drop.
Also, it seems like you use your laptops for a long time which means spending a little more money is not that much of a deal to you. Is the extra wait and spending $600 more worth the possibility that you will have to invest into a new laptop 1 year or 1 1/2 years earlier?
Personally, I would have waited because haswell is intel's "tock" of the tick-tock cycle. The cpu bump isnt whats impressive, its the GPU and battery life increases that will make the biggest difference between then and now. Since you do work that involves the GPU, having that new haswell GPU (HD5000) + 750m will make a world of difference.
But hey if youre happy with your choice then thats really all that matters!