Sounds like, given the reiterated criteria, that, for you, the Chinook is the way to go.
I only thought to mention the Epic fabric since you mentioned sudden rain showers - not sure how long/heavy they are.
Pertex prob. fine for "sudden" light to med. showers of a relatively short duration. I really haven't tried it in more extensive precip. So, I can't comment on its appropriateness for those conditions. I know both my Aero & Wisp will survive 10 minutes of moderate, large drop rain with absolutely no wetting - I could easily feel the drops hitting my forearms (short sleeve shirt underneath the windshirt) & the water just rolled off. Small drop rain just beads up on the Aero & Wisp & rolls/falls off when you move.
When it looks like extended light-mod. rain, I use the Epic windshirt. It's generally considered to be better for wetter conditons than the Pertex fabric, but less breathable. My BD Lightsabre bivy is made of Epic & survives hours of light to light-mod rain with no problem (if heavier, all night rain is in the forecast, I use an eVENT bivy).
For heavy all day and multiple day rain, sometimes w/almost no "let up" (yeah...we get that in CT & New England), I go with eVENT or don my poncho.
Hope this clarifies some points & proves useful to you.