My DS8 has special needs, also on the milder side (high anxiety, language disorder, etc.). He didn't set foot in a kids club until he was 7 and now I can barely get him out! They have structured and unstructured activities in the club, so if he wants to play video games or watch a movie he can do that, or take part in the organized activities. They don't have one-to-ones, but if you are going at a slower time, there may not be a lot of kids there.
One thing I would suggest, if you are unsure if the kids club will work out, I would choose a club other than the Poly or the one at BC. They have changed the programming at those clubs (a little more structured) and charge a flat fee of $55. A bit pricey if it doesn't work out and you need to pick up your son early. I would try WL, AKL or the Dolphin which still have hourly rates. At the Dolphin club, you actually get two hours of free care if you eat at a swan/dolphin restaurant and show your receipt. All the clubs offer dinner and snack.
I've also used KNO and they are excellent. I would not hesitate to hire them again. However, if you would like your son to be around other children, the kids club might be worth a shot.
The first time my son went to a WDW kids club, I was prepared to take him out after an hour ( though I knew there was a 2 hour minimum for payment). He surprised us and wanted to stay!