It DOES make a difference in tone, and it's been proven scientifically. Attack, sustain, and playability are all affected. Whether you'll like the changes is entirely subjective. I find that a bass with a Badass is much clearer and easier to hear in the mix then one without. It de-muddies the tone a good deal.
This has also been my experience with them. Attack, sustain and clarity are all very good things in my book...

MM