We're in our second year of Daisies. Our is a homeschool group, and DD does other homeschool activities with most of the girls. So, she knows them really well. We had a scheduling problem this year that almost made us drop it, but she wanted to continue so we're trying to make it work.
Now, the real benefit of our group is that it's a mixed age group. We have 5 or so Daisies, several Brownies, a few Juniors, and 1 Cadette. DD wouldn't like it nearly as much if it were just Daisies, and the leaders work hard to try to choose activities that can apply to the petals, try-its, or badges, depending on their levels. Lots of crafting, games, girls working together, field trips.
Ours is a very laid back group of mostly AP-esque homeschoolers. Parents all stay at the meetings (in our case, DH because I work full time). Many of us parents aren't keen on the cookie selling, but the girls enjoy doing it.
ETA: We've never done any activities outside of our troop...nothing at the council level, etc. I also really only see the benefit of girl scouts being the togetherness of the girls in their activities, meetings, etc. I honestly have a hard time wrapping my mind around the idea of being a solitary girl scout. I understand your difficulties, but I would just suggest that perhaps it would be better to wait until she is older, assuming the medical issues would lessen.
Holli