+1. It's equally proportionate Rob. Go twice as big, need to clean half as often. No more, no less. You need to upgrade a good amount to even notice. 33% (150 to 200) helps, but not alot.
Remember when looking at pricing that these things last a generation. Spread the cost difference over up to 20 years and it's peanuts if you only have to clean the huge one once per year.