Because we are talking kit and not ARF there will only be weak points if you build the weak point in yourself. All ARFs have weak points, the LG block is usually one of them. Sometimes you can't get in to the fuse to reinforce that area. A kit build is your own product, if there is something you don't like or think it could be stronger you change it.
The SSE is a fun little plane but there is nothing scale about it. It's designed to be a fun type of plane and help newer people learn stunt flying. The Extra was designed to be more of an IMAC type of plane, most of the kit Extras are not designed for 3-D. The ARF Extras you see today have been designed with 3-D in mind.
Off the top of my head I can't think of a 3-D kit Extra so if that's your plan you will have to make the mods.
I'm not a big fan of ARFs but if your thinking of a pure 3-D plane you may want to just buy one.
The plane I'm building now has some big controls and is very light weight. I will be putting triple rates on it. Just because I don't fly 3-D doesn't mean I don't like to try, I'm just not fast enough these days!!