How Deep Are You In: $how Me The Money

Having one major CC is good for you, using it wisely as you have stated.

Personally, I would keep 3 cards, with open credit lines. Use each one to make a $25 or more purchase every month to keep the account active and pay off the total amount next billing cycle. That will help a lot in maintaining a good score. Going down to just one CC could hurt you in the long run.