I posted about this subject recently and I've yet to pull the trigger....torn between 13 and 15 inch mrpro.
My experience for what it's worth on this subject.
Have two Lads, so that's 3 MacBook Pro's, bought 2 x 15" last year with Retina, 1TB (almost) SSD, 8GB RAM, bought 1 x 13", same deal.
I tried the 13" for my go away Photography needs (have an older 15" MacBook Pro that I used to use), found the 13" screen size just wasn't up to what was comfortable, clearly a better fit for weight etc, but the screen size just didn't do it for me, but the Retina display is a total Joy.
Couldn't convince either of my Boys to give up a 15" (ungrateful little People), so just ordered the new MacBook Pro 15" with the Haswell chip.
One of my Lads runs Windows (Games that only run on windows, poor deluded child), with Boot Camp, this 15" MacBook Pro has been back to Apple service 4 times with serious issues, the other 15" that only runs OSX (The smarter of the two), no issues, all bought same time, make your own conclusions don't want to get into a Windows/Apple discussion, about as useless as a Nikon/Canon discussion. My Lad ended up clearing the hard drive of the problematic Mac, returning it to OSX only, and taking My older 15" MacBook Pro and setting it up for Windows only, seems to work well when each Computer is only running OSX or Windows.
I used to run a 17" MacBook Pro, still have it in a cupboard, love the screen size, but don't believe I'de ever go back to the size & weight of the 17" when I feel the 15" just seems the perfect fit.
I see the Op mentions only running SSD 256GB, believe me you will find this just isn't enough HD space, I used to config with 500GB SSD (Almost), but now config with 1TB (Almost), and my new Order I've gone with the 1TB Pcle Flash Storage, another thing if you can pull on the cost, is increase to 16GB SDRAM, unfortunately by the time you push the new MacBook Pro specs to the limits, you now have a USD$3,650 Computer, but it's going to be a screamer, until the new one comes out, next year.