As the others have said, there is now a formal academic pathway and I think you would need a pretty good reason to deviate from that. It works well and has the right amount of flexibility built in at the right times. You can move in and out of the pathway but, realistically, it's probably harder to get back in once you've been out for any length of time. *
-Academic foundation programme (FY1/FY2): usually five clinical rotations and one four-month academic rotation.
-Academic Clinical Fellowship (ST1-ST3): largely clinical but 25% of time is dedicated to research. This is a run-through post and so you do not need to compete for an ST3 job in neurology - it is guaranteed as long as progress is satisfactory. You should spend the 25% academic time applying for doctoral research fellowships, i.e. money to support your PhD study.
-PhD: 3-4 years "out of programme" but guaranteed to return to training as an ST4 after your PhD.
-Clinical Lectureship: 50% research and 50% continued clinical training at ST4+.
-Senior Clinical Lectureship: equivalent of an NHS consultant but employed by a university. It will usually come with an honorary NHS consultant appointment at the same time.
-Professor: combined clinical/research role (proportions spent in each domain are negotiated individually - it's largely up to you) and bringing in lots of research grants.
In terms of pay, clinical academics are usually paid the same as their purely clinical counterparts. You do however have more control over your working week (fewer fixed commitments) and can negotiate odd extra payments depending on how much you are in demand. There are also clinical excellence awards, which can boost salaries considerably. The platinum CEA (rarely awarded) currently adds Β£80,000pa to the standard consultant salary. Clinical excellence awards are under review at the moment and it's not sure how/whether they will feature in the new consultant contract.
As you noted, the financial downside is that it can be difficult to balance NHS work, research, and private practice. Most academics lose out on private practice for this reason but I don't know whether that's necessarily a major consideration for neurologists (outside of London) anyway. That said, some clinical academics make a good private practice living as patients like to see the professor...*