Meira is someone whom I expected to crumble in WC2006, filling in for Andrade. He actually fared rather well -- and has consistently in the past couple of years.
That said, I don't think he's better than a backup for Juve purposes.
And despite other opinions about Meira from my fellow Portuguese NT fans here, Carvalho helps you win championships -- not only in defense, but in his pressing counterattack abilities (he was the prime difference for Chelsea's lone goal against Liverpool in many, many CL matches). Meira is a fill to help you survive in a pinch -- he plays above his abilities, but often he's in over his head against tougher competition. There is no comparison between the two.