I can share as bieng the wife of one. I know Marigee just got certified here with National, and my hubby has been a NSP volunteer for 20 years now.
I don't know of the parallels between Canadian and US system. I've been closely involved as a non-patroller at different levels over the years, and for the last 7 years I basically ski with him all day on his weekday duty day until he has to do patient care.
The training year is usually hell. OEC is a huge commitment (2 1/2 months, 2 nights a week in the spring), and then there's on the hill training. Our patrol is every weekend from October through New Years for on the hill training... talk about no free time... Our mountain gives family passes to ski patrol, (spouse and kids) and then there are pro purchase bennies, patroller exchange benefits (tickets at other mountains) We can go almost anywhere and he goes over to the aid room and can almost always get a day ticket. Other than my season pass I don't personally get to avail myself of his benefits, but that's OK.
In sum, from what I see, it's really worth it in terms of the benefits, the community service, the cameraderie, the excuse to be up on the mountain. It's like a giant second family for us and an excuse to go skiing. You will certainly become a better skier.
The negatives would be the time training in the first year, having to be out in really sucky conditions, and the usual BS you get in organizations involving egos, power trips, and personalities and so on. There may be costs involved for dues, training, uniform and so on.