Oh, this is looking wonderful! Nicely done--a credit to both you adn RobA. How far along are you toward producing "on paper" the end-map that's sitting in your head? I see a few things stylistically that stick out to my eye (ex: the extreme softness/blur of the map), but perhaps you're not done yet?
Also, most all your rivers split downstream, which is geographically possible but atypical in our world.
This is looking great, though!