Sorry for hijacking this thread but if Josh says something like "new editor", I think I want to add something. Its just a recommendation. The good ol´hammer editor had this baby here.
https://developer.valvesoftware.com/wiki/Hammer_Vertex_Tool
At the moment, the shapes and operators are not enough to make any shape. for example roofs.
The other benefit is, back in my days we had FPS problems as well, so to maintain a good performance we used triangles in combination with this tool. for example rockformations, uneven grounds etc. what kept perfomance high and allowed much more varieties.
To come to an end, I just want to say, this tool is very useful and should be added.