Gotchas with four violins?

According to the sound crews I've worked with, it's accepted wisdom that 
pairs of violins playing in unison will always sound dreadful. 
A few sound pros even expand this principle to say, "Do whatever
it takes to avoid small, even numbers of stringed instruments."
(There are more thoughts about this on my blog at 
<http://www.churchviolinist.com/2008/03/more-on-duet-dissonance.html>.)

So what's the best way to handle an ensemble which has four violins? The
natural way to divide them is two unison duets (2 on Violin I, 2 on Violin

II).  Is this asking for trouble?  I suspect that the problem isn't too
bad 
if there are enough other instruments in the mix, or if one avoids point 
mics close to the instruments (thus allowing room acoustics to blend out 
cla****ng pairs of harmonics).  What's your experience?  If groups of four
violins do pose a problem, how do you mitigate it?

Paul