I haven’t owned Vandersteens to-date but at this point am planning to get either Quatros or Kentos into my primary system, hopefully in the not-distant future.
My primary system has had Vivid B1s for a few years now, and they’re friggin’ amazing IMO. I’m only (likely) switching to the Vandersteens for their powered, contourable subwoofers that are essentially full-range (my Vivids don’t go down quite as far and don’t have the bass equalization factor), plus my liking for the Vandersteens’ time/phase coherence (am especially excited to get them for my classical music listening, which is about 40% of my total, predominantly orchestral works).
Both lines of speakers (at least the better Vandersteens) use pistonic drivers and offer what I regard as exceptionally balanced and spacious sound with great timbral accuracy. The Vivids are exceptionally dynamic, the comparable Vandersteens a bit less so.
Some years back, Peter Roth at Soundstage Ultra did a wonderful comparison of the house sounds of the two speaker lines.
Tradeoffs!