I know you can never know what is going to happen the future but honestly, so many things matter: how long you have known each other, what you can do to minimise the impact on both children, how compatible your parenting styles are. How do you resolve disagreements when you don't just agree. Do one of you sulk, shout, just expect to get your own way?
It's very easy to focus on the much nicer house you get together and forget about having to negotiate everything
DH were an item for nearly ten years before we moved in together. We thought we knew each other pretty well as we had been staying with each other a lot. We had more arguments that first year than we had had throughout the whole relationship.
Even though we are good now, if there were DC involved I don't think I would do it. To go from full independence to sharing space is just too much.
Thinking about it, why is it up to you to move and disrupt your support networks. Very easy for him to continue as normal. If it doesn't work out, will you feel stuck there with your child settled in school.
Saying might as well go all in, well that's great if it works. If you go all in and it doesn't work out, you may feel that you are trapped. How can you avoid that?
How compatible are you when you disagree? Will one of you just keep quiet for the sake of the peace? How would that work out for your DD?
How can you be sure that your child will not be disadvantaged ?
If you really love each other, you will still be around in ten years.