I have a small knowledge of GPs as commissioning consortia, though I'm only voicing my own opinion here.
The main strength that GPs bring is a long-term view. The GP as partner in an independent business is here for the long term (the salaried GP isn't - average tenure of a salaried GP is less than 2 years). The GP partner sees patient x and knows that decisions made today will affect the doctor, as well as the patient, for the next 10, 20, 30 years. So they make the right decisions. I'm sorry, but hospitals don't take this view because doctors and nurses move on. Sadly, PCT managers also don't take this view because they too have moved on to other specialities and other responsibilities. Independent GPs are best for patients, but they may not be the best at commissioning services.
6 years ago, before the last major reorganisation (merging PCTs from 303 to 152 PCTs), hospitals ran rings around PCTs because the hospital was much bigger and had all of the information. Hospitals took money hand-over-fist and attempts to move care closer to home didn't work. At present hospitals and PCTs are about the same size, and negotiations are a bit more balanced. But the proposed change (still 150 hospital trusts, but around 500 PCG-type organisations; also many district nursing teams will become part of their local hospital) tips the balance back in favour of hospitals.
My only hope is that this move by the coalition government is a prelude to the complete transfer of health into Local Authority control, with elected representatives in oversight and joined-up planning and implementation.
But many GPs strongly resist taking on the responsibility for commissioning, especially as they will inherit all of the poor decisions of the previous system, including long-term wasteful contracts for independent treatment centres, contracts with community care and hospitals that GPs have already said are not fit for purpose, most of the staff (because of TUPE) and only 1/3 of the money that PCTs currently have.
The most likely scenario is that GPs will simply take early retirement, leaving patients with no other choice but to go to hospital (in many cases, the most expensive route; and certainly not likely to give them the best care). Private companies will step in to fill the gap, but because they take a short-term view, the £billions will go in profits rather than proactive care. Tudor Hart will be proved right, 40 years on, as GP consortia step forwards in the most lucrative areas, and the deprived areas lose what little they already have.