realskiers

The skinnier ski with a race pedigree (if not an actual race ski) becomes very condition specific, and is certainly not 'necessary' to enjoy firm conditions.   

Liam:
I agree with everything you said EXCEPT for the part that assumes that the "skinnier ski" would have a race pedigree. Both Lynn and I have 72mm waisted skis, neither has a race pedigree, and both were bought for their versatility. And I have skied mine in 8-12 inches of powder without complaints. In fact, my 72mm waisted ski is easier and more versatile (for me) than the iM78's that I had several years back.
But I now agree with the two ski quiver concept as long as the extra weight of hauling two pair on the airplane can be dealt with (or you are fortunate enough to live slopeside and have your entire quiver at hand).
And while its been said many times, I can't help but remember buying a K2 Axis X some years back as a "mid-fat" at 70mm to replace my iC160 at 66mm.  Now my 72mm skis are the skinny skis.