AKV as of now is the only DVC that has that. I'm curious to see if the others don't follow suit some how. As of now we are safe with the impending little one. We should be able to get away with a 1 bedroom for a few more years, I hope.
Also don't forget that when you go to Disney I beleive Florida has a occupancy law of only four to a room. So even if you go through CRO you could run into the same problem unless you consider the family suites at some of the resorts.
You may want to check out the occupancy thread - go to the sticky at the top of this page and click on ongoing topics and then occupancy
They have been allowing 5 in a 1 bedroom at the other resorts with the understanding that they will not provide the extra bedding and towels needed for the 5th person. You would need to provide an air bed, sleeping bag etc. for that person. That policy may aor may not be continued.
I am not sure about the occupancy law, but mousesavers states that some of the standard rooms at the deluxe resorts house 5 plus a child under 3.
For example, Polynesian.