OP, gotta congratulate you for sticking to Dave's plan and getting the balance paid down.
Our credit system is a** backwards, and I've run into the problems from the other side of the spectrum. I needed a car loan and had NO credit. You would think not owing 10x what I'm worth would make me a good candidate because it demonstrates I actually live within my means. But no, I had to jump through many hoops to get a car loan even with a 50% down payment. A year later, I was approved for a 2nd car loan, and 6mths later I've been receiving CC offers about 1x per month.
In reality - if you stick within a reasonable budget and prove you're willing to pay what you owe, have closed accounts will not hurt you - it is actually the more responsible thing to do rather than let those account sit there with available credit that can be used. If you keep 1 open plus a car loan or mortgage, you're proving you are a good faith payer and can handle the responsibility, and that should keep your score up. I do not think having credit available beyond what you could realistically pay off in a lifetime demonstrates credit worthiness.. more like train wreck waiting to happen. Hopefully, the credit bubble burst will bring banks around to see this logic.