My daughter was in Montessori (the La Jolla Village one, not the Mt. Soledad) for pre-school and we loved it! Yes, very academically oriented which I am pretty sure that most of the places you are talking about are not doing. (However we don’t have direct experience with the others). We liked this particular school because it was a “lighter” version of Montessori implementation. They weren’t quite as strict and regimented and quiet as we saw at others Montessori schools. they were more flexible and accomodating. Kids were happy and still kids.
Many of the parents in our class are sending their kids off to K in public schools (La Jolla).There are a few that will continue with 1 yr of Montessori kindergarten at the same location.
If you are looking for about full-day accomodations anyway , I don’t think the fees are quite that much different between different options. The extra bucks are worth it, IMHO. Ours is about $1000/month (till 3 pm) and $5/hr until 5:30 pm. Montessori however has more vacations/breaks/holidays so you have to plan for that (i.e. camps at YMCA, Kids Ventures, etc.).