Sitting on a train with time for a bit of input here. Read the thread. A word of warning based on our own experience after 8 + years in the private sector with different children.
Now is an exceptionally turbulent time in the independent sector and you need to remember that whilst it is relatively easy to leave the state sector, it can be very difficult to go the other way, as you are effectively "out of the loop".
In our case, over a 5 year period, our independent junior school dropped from a roll of around 70 to 27. Caused by a variety of factors - local over supply, the opening of a nearby private co-ed which started sucking in girls, the recession etc. But salaries have to be paid from somewhere, and as the roll falls, fees go up, and discretionary staffing - specialist music teachers etc start to fall away. Fees have increased very significantly... Many parents who opt for private schooling tend to do so because they are attracted by the autonomy, self regulation and responsiveness - and on a day to day level, this has always been the case - but then when the school hit the buffers and had to merge with another school, we discovered that in fact as parents, not only do we have less power than in the state sector, but the school is owned by an unaccountable charity of do-gooders - the great and good who give their time for free and retired military types who do their best but who have no experience of change management - this translated into one of the most stressful and demoralising periods of our lives - very upsetting and a strong sense of £100,000s wasted.
So have a look around at where these schools sit within the broader plan for school provision in your area and try and think long term. I suspect, for example, that new free schools, as well as expanded grammars, depending where you live, are going to be the undoing of many midrange independents, along with a growing trend to move back into the state sector for a level.
And the other rather grim (sorry to be so negative) reality we are starting to have to deal with are friends disappearing at the end of term because they can't afford to pay anymore. Whereas, 5 years ago, the school would have worked something out, the climate has changed now, and more parents falling into difficulty mean greater demands on limited resources, combined with a need to behave in a more transparent and accountable manner because of the charitable status issues.