I know topic is about powers, but I think is pertains. My feeling I've had is sometimes progression in general feels slow. When I play solo, I'm fine with the pace. But when with friends that play only a few times it feels like it drags.
Next time we play I'm trying some changes... I'm looking for discussions on the topic. The tread gets me thinking it would be ok to speed up the powers acquisition since I'm speeding up items a little.
Im seeding boons and it seems to speed it up in a not too crazy way. When starting fresh, I remove all cards with the 'basic' trait. Sprinkle with some useful basic stuff if needed because of composition. Rewards I consider "the box" to be current and last adventure levels and throw in one adventure level higher item. It's a balancing act to get it right.
The thing is it only changes the pace of acquisitions of power up items. I'm toying with the idea of a character cache or stash. So that character progression isn't simply vertical +1 bonuses countered by the monsters being slightly higher difficulty.
With people I play with we don't end up gaining many powers because we need to fill holes with character classes etc. I'm thinking with a cache of cards to choose from to build the deck before play people will be more inclined to keep the same characters. Which will in turn be more satisfying when they only play a few scenarios.