Choice of Vandersteen models

I'm pretty sure the Quatro Wood will have the "tri-woven" midrange driver. If the model 5 pre-dates that driver, the decision should be much easier for you! Then again, the model 5 can be upgraded to 5 Carbon.

Midrange suckout? Are you referring to Stereophile's measurements? That "problem" is because Atkinson has to measure at 50" in his "quasi-anechoic" technique, and he doesn't always use the manufacturer specified height. This severely handicaps first-order designs in particular. Compare, for example, Stereophile and Soundstage's measurements of the Thiel CS2.4. Stereophile shows a big "suckout" in the upper midrange/lower treble while Soundstage shows near ruler flat response from ~35-20K cycles. Why the difference? Soundstage has a real anechoic chamber and, more importantly, measures at 2 m = 79".