Can current 13 rMBP handle two monitors with ease?
I worked with a 13" rMBP, which was connected with two 2560x1440 monitors, a few weeks ago. The performance was good, although animations (e.g. mission control with many windows) can get a little sluggish. The performance gets worse when you use two monitors and the built-in display simultaneously, but you will notice it primarily during animations or graphics-intensive work.
For comparison, I returned the 13" rMBP for various reasons and got a 15" rMBP with 750M graphics, which is driving the two monitors and the built-in display without any lag. So while the Iris graphics should deliver enough power for your current setup, the faster processor and the dedicated graphics card can make a big difference if you are planning to add a third monitor or switch to 4K displays.