The 330 will work for all the analog traffic in OKC. Even if you get the 396, it will not be able to track the digital used in the new EDACS system (just search for ProVoice and read all about it).
The only APCO-25 digital (the digital mode that the 396 decodes) in OKC is the federal stuff now (and some crazy hams running around on simplex!). The federal stuff includes Tinker security, the VA hospital security, TSA at the airport, and the Federal Transfer Prison out by the airport.
There is talk about a statewide 800 MHz system, and I don't think anyone knows what that's going to be, but I would think it might turn out to be digital in the future. If you think you could get a P25 radio in say, 5 years, I would probably just stay with the 330 if you're not into listening to the federal stuff listed.