Digital BW, The Print

Hello:

i really like Epson's 2 papers, Archival Matte and Epson's Watercolor with 
Piezo/Gen mix(I'm using Paul's formula in which the yellow position gets 
mixed w/ ltMag and ltCyan-thank's Paul).

Here is my question:

Are these papers really long-lasting, as far as avoiding a shift of the paper 
towards yellow over time(1-2yrs)? Also, now that people have had some time 
with the prints under window light tests, how do the paper bases look?  Is 
anyone finding any strange reactions with the Piezo inks and either of these 
papers over time?  

Also, some papers buckle a bit in the middle under a mat, even at relatively 
small sizes and I'm curious if people are seeing the problem after an 
extended period or if anyone has heat mounted Piezo or MIS work, please give 
some comments.

Thanks,

Andy Darlow