I was in pretty much your position two years back, but a year ago we did take the plunge and move in all together.
Overall I think it was the right decision for us. Some things have been hard, and some harder than I'd expected. But other bits have been really positive. There were some tensions between our DCs at first but these have really smoothed out and mostly they love having each other around, which is great.
The things that are harder are that I've lost my autonomy. I don't see as much of friends as I used to, and I used to put people up for the night much more easily. My friends knew I was really relaxed about that, but don't feel they can impose now I'm with DP.
Harmonising house rules beforehand was something we put some effort into - and that has been worthwhile. House rules are still pinned to the fridge, and mostly followed.
The other thing that's still hard is whether we're co-parenting or each ultimately in charge of our own DCs. We kind of share a lot of the parenting of my two and DP's younger ones, but I find it very hard to parent his teenagers (who are older than my DCs), especially the one that's busy trying to be a rebel at the moment. I keep thinking that if she was my DD we wouldn't have ended up in the situation we're now in with her because I wouldn't have let it happen. But if I say this to DP, it's obviously not very helpful to him. So I have to support him to find a way out of a situation that I can't help but feel is his fault for not parenting her properly in the past (eg not checking with friends' parents where she's staying overnight beforehand). Whereas when we had separate houses his lack of parenting of DSD didn't really affect me. Unlike the house rules, I think the role you'll each take with the DCs isn't something you can really work out beforehand, as you have to just see how the relationships develop. DP is comfortable disciplining my DCs and would like me to do the same with his, but with his older ones, I just can't. I don't feel I have that authority.
It is nice living together though. I do really like having someone to share my life with on a day to day basis as well as on "date", and I think we both like looking to a future together. It's financially a good deal for us too, and in many ways easier in a practical sense.