Excuse my ignorance; I haven't shopped Campag wheels in a while. Despite that...
Campag tends to use proprietary stuff.
They also tend to do things a bit differently. Look at the lacing. Proprietary spokes.
Shamal Ultra? Paying more for ceramic bearings.
BTW, if you are running Shimano, you probably have to look to Fulcrum.
For what the Shamals cost, I would rather go with a custom build, using regular parts easily serviced by me or the LBS.
Something goes south on your Campag wheels and you are probably in for a wait to get replacement parts.
Quality wise, I would guess they are about the same. I just wouldn't want to deal with replacing some propriety aluminum spokes (if I had to guess, at least 2 or 3 different lengths) or other Italian carbon/alloy goodness.
If you take care of them I would bet a long and happy relationship.
All my bicycles are Campag and I looked hard and long and Campag wheels.
In the end, White Industries, Sapim, and HED won out.
Don't listen to me.
You gotta ride them and look at them everyday.
Get what makes you happy.