Good simple semiPR methods?

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 votesplitting 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 semiproportional without needing to go through many rounds (and that have fewer problems than cumulative)?

@anniek Sequential Ebert is precinct summable and fully proportional. It still has rounds but doesn't require counting ballots more than once. Might be what you're looking for.

A simple way to calculate sequential Ebert is to add for each already elected candidate, the number of voters who voted for both already elected candidate and considered candidate divided by number of voters who voted for already elected candidate. Then plug the sum into Sainte lague formula as number of party seats.

@matija Thanks, I'll look into it.

@matija Is Sequential Ebert simpler to administrate than SPAV? It's also nonmonotonic though, which could be seen as a problem.

@tobypereira It's simpler to count and simpler to compute. ABC+A+B+C might be slightly more monotonic and is equivalent to using d'hondt formula.

@anniek said in Good simple semiPR methods?:
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 votesplitting and bullet voting. Where can I learn more about these effects in cumulative voting?
The main problem with cumulative voting is what happens if they don't do bullet voting. Cumulative voting produces kindofproportional representation if voters are strategic and perfectly informed, because minority groups can coordinate to bulletvote. However, too much honest voting by these groups can easily result in a bare majority sweeping all the seats; in other words, requires some very complicated coordination (especially in small elections).
I don't think there are any proportional methods simpler than SPAV except partylist representation, or possibly sequential Ebert (although I'd consider sequential Ebert about as simple as SPAV).
Have you asked what makes this group think of SPAV as "too complex?"