IMO...
Reasons for putting Cambridge: Teaching methods (as you've said), notoriety would enable you to go to other places nationally and internationally in a stronger position, beautiful place, Addenbrookes Hospital is world-renowned and prices at Cambridge are far cheaper compared to London prices particularly for accommodation. Also, I know someone who was pooled to Robinson College for Medicine and she had a really great time and wants to do medical research now back at Cambridge, so she had an enjoyable time as well as having really great career prospects.
However...
As you rightly pointed out it would be hard work, but then and again Medicine is a hard course regardless of where you go! At Cambridge you'd just be fitting all the same/similar content into fewer weeks per term which could cause lots of extra stress. At London Unis, you would have greater access to all of the amazing facilities and a greater number of hospitals than at Cambridge.
However, if University life is a big factor, also consider the fact that at London you not only have the more expensive prices but also you do not have the nice feel of being in an exclusive University town (you should probably ask some current students though for their opinions because it may not be as bad as I am making it out to be).
Ultimately it is your choice and particularly for a course like Medicine, it does not matter where you go because the end qualification is going to be the same! London Unis are amazing and very well ranked internationally too - no one should force you into accepting Cambridge just because it is 'the best uni in the world' (which it isn't). You need to go with where you are most drawn to because the more you enjoy being at that place, the more you'll get out of the course and the people teaching you. Lots of people turn down Cambridge because they simply realise it is not for them, and in a lot of cases it really isn't the right place for them because it's such a different level of rigour. The problem with TSR is that you feel like if you don't go to Oxbridge you will have basically failed at life which is 100% not true!