Works fine on my side. I copy and paste layouts and event sheets xml files and objects animation files from one project to the other, then open .caproj files in notepad and copy and paste xml code refering to plugins, behaviours, objects, families, layouts and event sheets from one .caproj file to another. Maybe that's what zenox98 calls "serious XML hacking", but hey, it works!
But I guess using SVN or Git, as proposed by Ashley in that tutorial, could be even easier. In my case I'd need something that allows merging two different projects, and not two version of a same project. (I think some project merging utility could be made using Construct 2 itself. I might try creating that.)