Perhaps my specialty is / was an outlier, but their capped salary was well below median MGMA and fell closer to the 25% MGMA figure. That was enough to prevent me from expanding my carbon footprint with a needless flight out to the desert.
I suppose a system not being production based would be attractive to the lazy, those lower on the income ladder, and those wanting to get all they can without actually working for it (or those in a profession that is suffering from a glut of providers, resulting in a situation where there is not enough work to keep everyone as busy as they would like)... but I fear that the products of this system will suffer as a result. The unavoidable fact of the matter is that our very job is one of piecemeal work, and should be paid for as such. Two biopsies on different patients, two units of service rendered, two people paying for the service they benefited from. Any system other than this either unfairly allocates work or reward, and often both.
The doctor, plumber, electrician, cabinet maker, etc should all be paid based upon the work they do for an individual. If a doctor provides a necessary and good service for 10 people, and another provides an equally good and appropriate service for 20, the one performing more work should be reimbursed accordingly.