Perhaps a bit too seamless as there is no indication of which instance users are from unless you go and check their profile. I can see this becoming an issue down the line, so I picked up a userscript that fixes the problem (it has other features, but that's the one I mostly use it for).
I use the same script! Its very nice to see which instance a user is on and the community/mag is on. I love how they can all be different and it just works. It's already feeling very natural.