I also feel that the space at the top of every page (header) between the member avatar (on the left) and the return Turtle (on the right) is rather plain and could have something else added to there, but what?

I agree with you on that one.  Just seems like a little something is missing but what?  If I think of something I'll let you know..  But Over all the board looks Great.  Very sleek and modern.       And yes not too dark.  Thanks for your hard work Mike.

Also, this forum seems much more streamlined and quicker with everything I do. Anyone else notice this as well?

Yes the board is much faster, now it's time for the Acid-test.  the Search Function.