All I know is that the Salutatorian from my highschool, who got a perfect on the ACT, is a ChemE major at Vanderbilt. All his status' on FB are about how much his classes suck.
Although one year of engineering isn't a great view on giving tons of advice about the ridiculous upper-division classes, what I would tell someone to do is to try it out the first year. You will DEFINITELY get a feel for what the program entails, but it won't be ridiculously hard, and shouldn't sink you. The vast majority of attrition in engineering students is freshman year. Besides, you will be taking mostly pre-reqs (chem, physics, and if BME, bio).
The guy EyEnStein 07 was talking about is ChemEngSoonMD