Yes, the Legacys sound great with rock. After all, they will absolutely scream at loud volume levels that the vandersteens could only dream of. They also have 2 12" woofers. The vandersteens may be powered, and you may be able to "boost bass" on the back of them....but the Legacys bass is one of the best Iv'e heard with a nice amp. If positioned correctly, they are just incredible
Legacy speakers are rolled off, warm and relaxed. If you don't like that sound, I wouldn't get the Legacys. However, Ive never heard speakers sound so good with so many different types of music, as well as so many different recordings. They play everything extremely well.
I have owned Martin Logan Ascent i's, Martin Logan Aeon i's, Magnepan 1.6's, Paradigm signature s8, and more...nothing has come close to the Legacys. IMO the older Focus 20/20's are the best value out there for under 3k used.
Personally, I have a thing for old school big driver speakers. Unless I'm sitting at a desk, many speakers just don't do it for me. I need that large sound that feels like you are there. I need a speaker that can do it all. For me, thats what a good speaker does. I don't like speakers that sound good with only 10-20 albums.
My day job is a music director at a church. I also lead the sound team. I sing, play sax, drums,and other instruments for a living. I also run a local studio. IMO NOTHING sounds more real and beautiful as the Legacys, Magnepans, and Logans. Out of these, overall I'd go with the Legacys...as they do more, and sound consistantly the best.
As far as imagining, there are speakers slightly better. As far as detail, speakers that are slightly better. The bottom line is the Legacys are for people who just flat out love good sounding music. I mean these things just sound incredible.
Sorry to talk the Legacy Focus up so much on these forums...but I really just love them. I sold mine about 2 years ago, and I have regretted it everyday since. Eventually, I will buy another pair.
I have heard the quatro'sand for me they are over priced, and not worth the money. Everyones different and therefore hears differently, so only you can decide which you prefer.