It's 'a' purpose. Both of us would be doing the flight anyway, because we are passionate about doing it. So it's a straight choice between flight with no charity, or flight with charity; we went for the latter, and the charity in question have been very happy so far.

Well done and good luck.

Might even sponsor you.

Thanks for the good wishes :)

Did this ever take place or is it still being planned?

Hope not.

Just as a side - the 100hr checks are only mandatory for for hire aircraft in FAA world. If it's for private use, then you don't need to do anything but the annual.