I think there are several seperate issues

First, what is your status after using AP,
I would say AOS.
Second, do you have to use EAD to work because you are in AOS status?
No, you can use H1 as long as it is still valid.
Third, can I go back to H1 status?
Yes, through H1b extenstion or transfer and get a new I94.
Fourth, if you get a H1b extension without I94.
I think you are still in AOS status, but you can continue work on this new H1.

All these are just my understanding. Consult your lawyer before making decsion. However, I haven't seen a single post that using AP caused any trouble.