The best school of thought is a combination of both. Of course, that can get expensive and need a larger crew of programmers to get it done.
You have to rooms. One room is perfecting AC on the EMR side. Make the letter writer more robust, make orders a little more seamless, enhance the abilities of the scheduler to match competing EMRs. These people should be testing other EMRs that people like and figure out ways to bring AC to that level in the weaker areas. Go to several docs offices like Bert's or mine and watch how we use the system, where it slows us down, where it can be better, where it shines.
The other room is the room to keep you from getting left behind. Its the PM developers. These people need to have a hang out with actual billers in various specialties offices to see what is most needed from a great PM system. AC will find out that there is no perfect PM system in existence and I doubt they nail it on the first go-round.
Both rooms need field experience in more specialties than just family practice. On these boards we have general surgeons, ENT, ophthalmologists, peds, IM, GI, FP, Nurse practitioners, ortho, PM&R, etc. So a broad range with broad needs. In the end, we all need a good documenter, report keeper, scheduler, orderer, letter writer.
