I'll share a little bit of input from our many years of MFW. We've used Adventures, ECC, CtG and are starting RtR. I do have a daughter in High School and the flexibility of the history cycle has allowed her to join with us in the cycle, by only 'beefing' up the program a bit with additional independent reading. We did NOT buy the High School program, but instead used the lower cycle with just adding in the recommended resources for HS. A much more cost effective alternative for those with larger families.
I love the "open and go" method and now has even been a special learning tool at teaching my daughters a special gift-- learning how to homeschool themselves. It allows me additional quality time to plan for other events like coordinated field trips with the topic of study. I want to pass along encouragement and strength to them to homeschool their own children. They feel very privileged to be teacher for the day and at the same time it gives me the flexibility to juggle other things in a busy family. The retention level when "teaching" siblings seems to be much greater as another added benefit.
Just wanted to share a bit. Great topic and I've really enjoyed reading the input of others on both programs.