Your replies may trickle in a bit slowly for this question, mainly because of Christmas taking up so much time and energy. I'll try to start the ball rolling.

In my experience, waterproof-breathable fabrics rarely fail to be waterproof at the start of their working life. Their problems almost always relate to their breathability, which is easily overwhelmed by perspiration when you are working hard, such as hiking. This allows moisture to accumulate inside the jacket and may appear like a failure of waterproofness to the wearer. Unfortunately, the breathability of every WB fabric can fail, and even the best of them are only fair to middling in real world conditions.

One factor that can cause poor breathability is when the DWR (durable water resistant) finish stops beading water, so that heavy rain coats the outside of the jacket with water and prevents the pores from releasing water vapor. The thing to do is to renew the DWR finish. There are products for this.

Another factor that can cause poor breathability is when the ambient air temperature and humidity are not much different than the warm, humid air inside the jacket. There is no simple or easy cure for this other than taking the jacket off. You're going to get soaked either way.

Overall, the best solution to perspiration is ventilation. Open the collar as much as you can. Use any pit zips provided. Add an umbrella, if it isn't too windy. And wear a base layer inside the jacket that wicks moisture away from your skin and isolates your skin from the moisture that is inside your jacket, so you don't feel the wetness, even though it is there.

As for the two Marmot jackets you are considering, I expect either of them will perform reasonably well, given the inherent limits of the waterproof-breathable technology. Have fun on Vancouver Island. It is full of lovely rain forest.