It's that time of the year when new comers to Qatar begin exploring schools for their children. Good luck with it all. It is not an easy process. But I think it would be more helpful if people spoke from personal experience and based on evidence. Impressions and second hand information can be misleading.
BTW, my kids go to Sherborne, and I am pleased with it. I don't think it will be comparable to the Dorset school. It can't be, and I don't judge it on that basis. I judge it on the curriculum, staff, activities, interaction with parents, etc. As for fees, while it is not cheap, it is less expensive than Compass, ASD, and ACS Doha. I think DESS is subsidized, right?
Good luck with ACS and when you've gone through the experience, please write about it. I am sure many people will want to know.