I don't agree that using 0w oils are going to cause cams and rods to wear out... not prematurely anyway. Also, I don't know of any facts or history to back that claim up. I love to see it though if it does exist.
I owned a 92 Taurus SHO (#1 son has it now) with 100k miles. The car has never seen a 10w oil. 0w and 5w Mobil1 for it's life and the cams are visibly flawless. I know folks with 250k miles with ow oils with no problems. I too have heard the [occasional]stories, but have never personally seen a well maintained engine fail because of a "light" synthetic. The SHO saw a lot of 7k runs and with #1 driving it, I'm sure that hasn't decreased. In Southern New England in 2002-2003, we had temps ranging from -10 to +100. Try cranking any piston engine over with 15w-50 engine at -10... It'll go, but the 0w oils sure make a diff.
Now, having said that, I might be reluctant to use a 0w oil in SoCal, or Southern Texas year round where temps are consistently over 60 ish degrees...
Pitty the poor second owner who has to shell out $15-20K for a new engine when the cams and rods wear out.
In the lower 48, excepting the real 'arctic' places that get colder than -10F regularly, there is no reason to use anything lighter than a 10W40. 15W50 synthetic is great for anywhere except Edmonton or Fairbanks or other similar un-inhabitable frozen waste lands.
Only the 'miracle' of cheap petroleum products allows man to settle in those places and drive cars anyway.