PAN membranes are negatively charged (sulfonate), while PES membranes have much less surface charge. My understanding is that PES membranes become fouled (blocked) by proteins more quickly than PAN membranes. PAN membranes can show a low recovery of postively charged peptides, but polyethyleneimine can be flushed through PAN probes to eliminate the negative surface charge and increase recovery of positively charged peptides:

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5118035/ 

Adding BSA to the perfusate should decrease protein binding for all of these membranes, though most our experience is with our standard polyethylene membranes.

PAN membranes display less ultrafiltration than PES membranes.