Not everything is about dollars and cents. On paper, everything will definitely look good. After all, the grass is always greener on the other side. I suggest moving over to try out for a couple of years and see whether everything works according to plan (and within your expectations). Keep a significant portion of your money in SGD in case it doesn't work out. No point chasing the high interest rates up North and having to lose everything if you choose to give up on your retirement plan and return to Singapore.
As regards the education system in Singapore, I think it's difficult to please everyone. Not every international school is decent - you have to do your research. Your kids may find education in an international school more enjoyable and less stressful. But it doesn't necessarily mean that they are getting a better education. It's really what you want in life. Speaking for myself, I am definitely going to put my kids through the local education system. About school being stressful, try looking at other Asian countries, such as Taiwan, Hong Kong and Korea etc. No point sheltering kids in a protected environment when they have to compete globally (or at the very least, regionally) when they grow up. Those who studied overseas (or studied alongside our foreign imports) will get what I mean. As a doctor, I am sure you are able to appreciate how stress can also have a positive effect, if managed properly. Just my two cents.