Although features around moving cards between decks, drawing from multiple decks, allowing tranches of cards to be released based on other sets of cards reaching maturity, etc. would get me to switch. I've been an Anki user for a few years, and the inability for Anki users to do simple things easily (or sometimes at all) is frustrating.
Having more than a few decks also slows everything in Anki to a crawl. The community has responded by dumping everything into an uberdeck (killing reusability, which gets sourappled), when we could instead be coming up with theories on how best to juggle multiple decks to maximize learning.
