Which rMBP for my needs? 13" or 15" rMBP

Question

Hi,
I've read several threads and articles and can't seem to find any reviews for folks w/ a similar setup.  Most reviews are for a the laptops themselves but I'm curious if anyone can chime in on the performance when connected to a 27" Apple display (pre or post thunderbolt).  How does a 13" rMBP perform in iPhoto/Lightroom/Photoshop on a 27" apply display?
Here's some background.  I'm currently using a 2010 15" MBP connected to a 2010 27" Apple cinema display (pre-thunderbolt) and performance really bogs down in iPhoto (150GB iPhoto size).  Performance is much, much better when not using the 27" display.
My current and future uses are iPhoto and iMovie.  I use a Canon 7D DSLR mostly for pics and HD vids of my friends and family.  I plan to purchase either Aperture or Lightroom once I get a new rMBP as well.  I shoot RAW files and use the HD video features.
Can anyone chime in and/or make a recommendation as to which rMBP would be best for my uses?  I like the price and form factor of the 13" rMBP but my main concern is it doesn't have enough horsepower to drive a 27" apple cinema display.
I have both a 2008 13" aluminum macbook, 2010 15" MBP, 2011 MBA, and all work like champs - when standalone.  It's just that they don't seem to be able to handle 27" apple display all too well (i.e. scroll lag, choppiness when dragging windows, iPhoto slider update lag, etc).  The 2008" 13 aluminum macbook can only watch Bloomberg TV standalone, on the 27" display it's blank.  My work laptop (2011 Lenovo ThinkPad) handles the 27" display like a boss!!
With that said, unfortunately, for my needs I feel like it's time to upgrade (again) and now leaning more towards the 15" rMBP.  But if the 13" rMBP can handle large RAW files, HD vids, AND a 27" cinema display I'll get that one.
Any help is greatly appreciated.  Thanks so much!

Answer 1

I also use a Canon 7D. One big difference is that the current 13" and 15" have Intel Iris/Iris Pro integrated graphics, which are said to be a great improvement over the integrated graphics in the older MacBooks you have. They are so much better that Apple no longer sells MacBook Pros with a separate graphics card unless you buy the most expensive 15" MacBook Pro, which is so expensive I'm not sure I'll ever buy it.
For Aperture or Lightroom, the amount of RAM is going to be very important. I don't use Aperture, but for Lightroom the graphics card is not very important. From that I would guess that you could get either a 13" or 15" as long as you put enough RAM into it from the beginning, since both programs want lots of RAM and you can't upgrade it later. That should be at least 8GB RAM, but I would just max it out at 16GB RAM and not worry about it again.
The current 15" should drive a 27" monitor without a problem. I'd like to say the 13" can, but since it's labeled Iris instead of Iris Pro that might make a difference. If you live anywhere near an Apple Store you should go down there and ask them to connect the 13" to one of their 27" monitors and see how well everything works.