My point was expat that you shouldn't play Google's and only Google's game. If you only worry about Google and they dump you, what will you have left? Those directories that you may or may not have submitted to? Link exchanges? ... You get my point?! DO NOT RELY ON GOOGLE! :> If you do, it's going to bite you in the a$$ someday.
I applaud you with such success...It's certainly not easy to accomplish that feat.
On another note, If it's not broke don't fix it! :> I'm sure you've heard that age old ado?! If I ranked #3 to #5 consistently like you have I wouldn't change a thing. Google might sandbox you for tweaking anything! :> Seriously!
And with the link exchanges it sounds like you are doing the correct thing so don't worry about it. Just make sure you constantly monitor who your linking to because sites can change in an instance.