I think I've mentioned this before but- there is a wide spectrum of what "Montessori" means. The school we were at is an AMI-Montessori accredited school, which most "Montessori" schools are not.
I personally think that the blend you are describing is ideal- sort of "follow the child" Montessori mixed with some actual structure.
However, generally "real" Montessori schools do not have homework or timed tests. They sound almost like unschooling. The problem there is that there is little accountability, and if your child doesn't want to write or read alot, they probably won't do that.
You are right--there is a wide spectrum! It is an AMS school, so yes, the teachers are more flexible than AMI. Many of them have also taught in the public schools, or other private schools, and while obviously they believe in the Montessori philosophy they don't mind tweaking it to fit individual child's needs. I am sorry your experience wasn't good.
