Hi, I've been developing with Construct 2 for some time and even developed some custom plugins and behaviours to give my games a personal touch and do some extra stuff.
One thing that I don't like about Construct 2 right now is having to leave all custom plugins, behaviours and effects whithin the installation directory. The way it is, I can't just install Construct on another PC and work with my projects unless I copy all the plugins. Even worse: it gets very annoying when you use some versioning tool and you want to version those plugins/behaviours. They have to be copied to/from the installation directory to/from the versioned directory at every commit/update.
My suggestion, therefore, is: leaving custom plugins within the project folder structure, so it can be freely copied to any other computer with Construct 2 installed (something similar to adding a lib to your project's folder in a coded project).