What do you think about Definitive Technology?

How do folks feel about these speakers for HT? audio? Am I wasting my B&K ref 30 on these? I've aready started buying (surrounds and center) but bought used and could sell w/o loss. I've been buying for about 1/2 MSRP- if that trend continues it will cost about 3500 for the definitve tech speakers (w/o sub). BUT if I buy used and spend 5000-6000 how much of an improvement would there be? and what brands would you recommend where the C,L,R, and surrounds go for a total of 5-6K used? Most everyone here is far more experienced than I so I appreciate the feedback!

Thanks,
Peter