Can you really?
I'm not so sure.
I think much is made of the superior quality of goat chevre leather over nappa lambskin. However, I think it's very misleading as we all know that there are some years - 04/05 - in which produced sumptuous chevre as opposed to 06 (sorry), which most people thought was a really bad chevre year.
The best quality goatskin is kid leather, which is young, supple, glossy, with visible pores, but marks as soon as you breathe on it LOL. I don't think that Balenciaga ever used kid leather in the past. I think they used an older goat. What we all like about Balenciaga leather is the combination of lightness with strength and fantastic distressing.
Nappa leather is amazing, having different characteristics, such as being matt, therefore not showing scratches etc. I believe it's a thicker than goat, with a greater tendency to wrinkle.
I think Balenciaga lovers are too dismissive of lambskin. If lambskin is inferior quality, I don't think Chanel, Chloe etc would used this skin for their finest bags and Lanvin for their pumps. It's not the type of skin that's good or bad, but it's the quality of the skin.
IMHO the F/W08 (nappa) leather Bbags were gorgeous, especially the bigger bags such as the work. I like both chevre and lambskin for their particular qualities. I think it will be a matter of time before we know how well the nappa wears over the years, but I like the idea that the Balenciaga bag is subtly evolving due to the use of different skins.