I'm also reading that Proclassic semi-gloss is pretty close to Satin Impervo in sheen, and Proclassic satin is pretty flat, anyone know if that's that true? If I get the Proclassic, I'm wondering if I should get semi-gloss instead of satin. I can't actually find a paint store around here that has the Satin Impervo, so that may not be an option.

A lot of painters have their preferences, however in my opinion Sherwin Williams Proclassic enamel semi gloss is the better choice, it brushes better with a longer work time, Satin Impervo tends to dry too quickly. I have been using ProClassic for years with great success. You should get the Semi Gloss, it does dry to a more satin finish.

Thanks for your response and advice, pro.painter, I picked up the paint last night and he is painting the trim today, hopefully it will look great when I get home.

I was not happy with the coverage of the SW pro classic recently used on trim compared to Satin Impervo oil used the year before in other rooms. I had my painter switch back to the Satin Impervo.