I tell you what Aetrion: When you've finally gotten to this peak of potential power, please post your character to this forum. Let us know how long it took you to get there (e.g. hours played) and XP earned. I am serious. I want to know.
And just to be clear: Your +660 XP character you described above isn't there yet. Not by a long shot.
I don't really know where that number lies, and it's a little ridiculous that people are telling me I have to find that number to prove it exists at all in a thread that is primarily a question about where to set the limits to prevent hyperspecialized characters.
You are asking this forum where to set limits on something everyone has repeatedly told you is not an issue. So yes, it is up to you to figure out where that limit its (hint: its where the snipes like to play). Furthermore, you've yet to demonstrate why you even need such limits.
And what exactly is "hyperspecialization" anyway? Why is it even a concern?