Hi L.,
I have the original MBTs and they are wonderful. I've tried the Reeboks on and they aren't as comfortable but don't know if any of the knock offs work as well as the MBTs. You can tell a difference even as high up as your lower abs.
Be careful if you're pregnant. They take a little getting used to and you can lose your balance easily, especially if you don't have an even path. Stairs are really difficult and you can't "catch" yourself if you fall.
Congratulations on your little one!
M.
PS Other than the potential of falling, lol, they strengthen the back as well. The concept was invented by a Swiss engineer.