Just one anecdote here. After doing the undergraduate portion of the LEAP program, I applied and was accepted to Georgia Tech's M.S. program for this fall (hence me being on this board). Not in any way because I was unhappy with BU, but because I applied to a few top programs just to see if I could get in. Now it turns out that I am actually going to stay at BU for the M.S.
In engineering, the rankings probably matter less than in any other field. The courses are generally the same at any decent engineering school, and it all comes down to which schools have the research that you want to get involved in. I've gotten advice from a lot of my professors and friends in industry, and they all recommend that I stay at BU because it will save me a semester, and is a more personal experience than an enormous program like that at GT.