Shelly,
Since you already know how to use a Rainbow properly I don't think you will have any problems with it. Yes, some people get a lemon and others simply don't know HOW to use one the right way.
I know people that love Rainbow and I know people that hate them and both groups have very good reason to feel the way they do. There are always products that some people love or hate but most are just neutral about said product.
I have had good luck with Rainbows and I plan to always have at least one in good working order. That said, Kirby is MY loved vacuum.
Best of luck with your new E2B, I hope to have one someday.
Justin