A group I'm tangentially connected to has decided to switch from sequential proportional approval voting to cumulative voting (voters are given a number of points equal to the number of seats, and each voter can give any amount of their available points to one or more candidates). I'm concerned because I have heard that cumulative voting is susceptible to vote-splitting and bullet voting. Where can I learn more about these effects in cumulative voting?
The group is moving away from SPAV because they want something that is simpler to administrate, but they still want some amount of proportionality. Are there any methods which are proportional or semi-proportional without needing to go through many rounds (and that have fewer problems than cumulative)?