I use YH's settings in my Asterisk. All works as one-stage dialing except the **9 portion, which has to be routed via AA for further dialing (2-stage). It is because that my Mobile phone number is included in my Trusted callers list to access AA.
The original speed dial prefix **8 cannot be used any longer as it is merged into the dialing rule in Asterisk extension. What we will use now is our pre-defined prefix, such as 118X. The advantage is that you can dial to whatever numbers you want with this rule in a flexible way.
I haven't tried the use of speed dial but I don't see why we can't.