sorry haven't read all thread.
With any home-based childcare (cm or nannyshare) the key question I have learned is -
would I want to spend X hours a day here myself, doing these things, with these people?
If not, walk away.
DS spent 2 weeks with a childminder at 10 months. She was lovely, cheap and the location was OK. She gave all the right answers to questions. But it was winter and they didn't do much going outside. She had lots of older children around before and after school, and they weren't very nice to ds as they were tired and crotchety . There was older kids' tv on constantly at these times, and a lot at other times. She also had a lot of adult friends coming to the house - I had no problems with any of them individually, nor did I think it was intrinsically unsafe - she was always there. But I felt the house was like a railway station and ds was having to meet a lot of strangers, which was exactly what I wanted to avoid with a cm. Also I loathed her decor and her heavy use of air freshener - ds smelled weird at the end of each day. I told myself off for being snobbish about this, but that's what I mean about seeing if it is a house you would like to spend time in. If it isn't, you are going to be miserable thinking about your child being there.
I spent a week trying to persuade myself it would be OK, gave notice for a week and spent a week off work sorting out something else.
I was lucky enough to find a nanny-share very locally and that has been perfect from 10 months to now, and as far as I can see it will continue to be perfect for another year at least. The time off requirements for the nanny are hard - I need several layers of backup for these days, but I have those layers (dh, granny 1, granny 2, key close friend) and to me personally, it has been worth it.
Not hugely cheaper than a nursery, but more flexible on the things I care about, and I think probably more continuity than I would have got from a nursery - although that's more of a factor of this particular nanny, who is very settled with her primary employer.