The transition from having Maisie, and possibly Dawn as well, at our current barn, where I'm there at least twice a day, do all the feed decisions and turnout handling, to the barn where Maisie (and Dawn at some point I expect) is going where I can ask for but not control things, will be a big one for me. Figuring out how not to worry when you don't control every detail is hard - I've had some bad experiences at boarding barns with people not paying attention - the horse that came in from turnout with a nail in its foot that no one noticed until I came to the barn (I still can't figure that one out since the horse couldn't walk with a nail sticking out of the bottom of its foot), the horse that coliced because no one noticed the warning signs, etc. Although I expect that having horses at home (not an option for me) can lead to the highest standards of care, boarding barns, if they're well-run, can do a job that is good enough to ensure horse health and safety.
One thing that makes this transition a bit easier for me is that my older daughter works at the new barn and will have her eyes on Maisie, and will be doing her turnout and bring-in handling for now, and I also feel that the barn does a good job watching out for the horses - for example, the head guy who lives on the property does an evening barn check on all the horses. I will also see my horse almost every day - I believe it's important for someone who knows a horse well and is observant to have "eyes on the horse" every day.
Things can go wrong at any barn, but I'll have to work hard at not obsessing about Maisie's care. I need to pay attention to be sure that things are good enough but without worrying myself too much in the process. These tendencies of mine also apply to how I work with horses, but that's a topic for a different day.