I posted an article in a similar thread that Blackrose started that made some interesting points. On phone but will link it later if you don't find it first.

One was there is a massive variety in ages children hit puberty so it doesn't necessarily hold that waiting will actually benefit in that regard.

Second was waiting a year but doing exactly same things won't necessarily lead to being more ready, growth is through experiences so depends on what they will be doing that year at home, which depends alot on personal family circumstances.
I would be inclined to listen to her daycare teachers for two reasons, 1. They have experience of many many children to reflect on. 2. I think children save their more immature behaviors for us as possible parents (as they should) so I think childcare do have a good perspective of how will go at school.

Your DD although may not have had alot of daycare has lots of exposure to other kids of differing ages through her cousins and is well travelled too. What does your DH think? What were your experiences of school - is your DD like either of you? What is the school like? They are all questions I would factor in.