Justine: I do actually believe that at some point in the future crowd sourced opinions via the internet will be a way that pretty much all of us evaluate professionals (health and otherwise) but maybe I'm just nuts .
Ah yes that would be true but the only site which has done this to any great success is TripAdvisor and frankly, they have much better systems in place to edit out the bollocks. And if you have a crap holiday it's a crap holiday and you get over it. Bugger up a kidney transplant on the other hand......... :(
I'm happy to have a book recommended on Amazon, get it and think it's crap. Each to their own etc. There is a low risk associated with making a poor choice. One might say well a doctor would not be practicing if he was that bad Harold Shipman for example but perhaps the time lag in picking up poor practice does not support this.
Without wishing to go all daily mail on you, it is implausible to suggest that by a group of parents building up a database, preferences of the over sixties will be guided.
It's like asking an 18-25 holiday rep to organise a Saga holiday 
Also, perhaps it's better we know no more than we know now. You can already look up the death stats of a doctor, you can already look up whether they are have disciplinary proceedings at the GMC against them. You can even go along to their surgery and sit in the waiting room and ask the person next to you whether they are a trollish megalomaniac and get exactly the same type of responses you'd find on the site you are expounding.
I base my decisions about doctors on bedside manner, professional record and gut instinct frankly. You are saying 'don't use those, use the opinions of others' which are just as likely to be wrong (in fact more so as they are based on say-so.)
Want to do something good with health - well there's a plethora of insurance companies offering PMI who would partner with you for family health insurance and you demographic are more likely to go for it IMHO. In fact PM me and I'll tell you about the one we are with, they are bloody marvellous and not too pricey but moreover they are very, very ethical.