I have a large (16kg) 20 month old DS and am expecting any day now. He is not yet a great long distance walker, so have invested in a double.
I sold my second hand bugaboo Cam for the new Uppababy Vista 2015 and I have not looked back. It is a fabulous single, with a huge versatile seat and an enormous shopping basket. Even as a single I LOVE IT! The only niggle is that it is not a small pushchair (although folds smaller than the Bugaboo Cam in my car) and is about 4cm wider than I would like it to be. I do understand why it has to be this wide, and if it was not, I would be worried about using it as double due to the tip risk.
I have not used it routinely as such yet, but plan to have the carry cot / car seat and the single seat when baby arrives. It is long and does need a little force to pop it up the curb ( i have used it with another baby!) but everything in life is a compromise. My 20 monther still has 2 naps per day, so the ability to recline was a must to me, and this seemed to have the seat configurations that I wanted.
I plan to use the buggy board as soon as possible, and wanted a well built sturdy pushchair to attach one to, as my boys are big (baby measuring huge too on scans). Ticks this box too.
Overall, not looked back having made the change for single use, and can not see myself being upset when using as a double.
I looked at the icandy - smaller seats, tiny carrycot and the clicky-hood would drive me mad and wake the boys!
Hope this helps