@longnumberperson
I'm a relative newcomer to this, however I've recently spent a lot of time researching and trying out various paddle types so I can make a stab at answering your question about twist and catch.
Teardrop blades with a pronounced spoon have a very strong catch (Jantex Gamma Rio is a good example). These are good for high-cadence paddlers, however there is absolutely no reason why someone who paddles with a low cadence can't use them. However, someone who has a long stroke might find that they get into difficulties with these paddles - inefficiencies when taking the paddle out, for example.
People who have a long stroke might be better looking to the more parallel sided blades.
Low cadence doesn't always mean long stroke; you can pull very hard, wide and have a lowish cadence (that's me).
A pronounced twist in the blade, in my opinion (and others) 'spills' water during the stroke and makes for a blade that is less tiring during longer racing. Personally, I hated blades like this, found them hard to control and indecisive in the water. I'd rather have a smaller blade.
