I can't speak to that commute 100%, but I'm pretty confident that you are not going to like it. What time do you commute at? In my experience I've had to do a couple of morning commute time runs to the Airport (so Eastside, Airport, back to Eastside) and traffic was always miserable. It moves long enough to get you there, but it's pretty packed and moving at like 20-25 for much of 405 north.
edit: Just saw your edit, I guess it probably wouldn't be that much worse than Snohomish, so if you did that this probably won't kill you.