I don’t think the Chinese track at SMIC would be as rigorous as the average public in Shanghai. I am sure that there is still a lot of homework but just less so than a local school. This is just what I gather from a couple of teachers that we know at the school.
The one hour of Chinese in the English track is not enough to get your kids speaking Chinese. Most of the students in the English track are not native English speakers (e.g. Chinese, Korean) so learning English is the priority.
SMIC can be hit or miss depending on your child’s teacher. There are some excellent teachers at the school but there are also some inexperienced teachers as well. Given the rapid turnover of teachers it is highly like you could have a great experience one year and a horrible experience the next.