I can confirm that the SP2 works great with a Dell U2713H daisy-chained to a U2713HM with both running at 2560x1440 (the SP2 can also remain on at 1920x1080 - although I turn it off as I find it distracting).
Here's an image of the resolution setup of each screen side-by-side –
And a shoddy photo of the setup –
Getting the resolution different on the monitors isn't the problem. I have 2 23'' monitors and so both of them are set to 1920X1080 just like my SP2. But the problem is that I like to adjust the text size on my SP2 larger to 150% while I want to keep it moral on the 2 monitors at 100% and it just won't stay like that due to a Windows 8/8.1 restriction.