I only chose approval as an alternative to FPTP because most current ballot-counting machines are capable of handling it with minimal alteration, and it reduces the effects of strategic voting.
It seems obvious to me that any voting system that involves ranking would tend to discourage more open ballot access, as people are more likely to honestly and accurately rank 2 or 3 people than they are to rank 10. If it can handle proportionality almost as well as single transferable vote, without additional complexity to the voter, it may actually be better fro ma practical standpoint.
Approval ballots is just a special case of ranked ballots with only two ranks, so as far as considering and honestly rating a large number of candidates is concerned, it shares any problem ranked ballots have.
While there are some good arguments for allowing ties in ranked ballots (unforced vs. forced preference), I think there are pretty big problems with forcing tied rankings.
> If it can handle proportionality almost as well as single transferable vote
I don't think it can, but because there is no clear mapping between actual preferences (or preferences that would be provided on an unforced preference ballot) and approval ballot (or any other limited-rank-preference ballot) markings, that's a hard empirical question that's not really analytically addressable.
It seems obvious to me that any voting system that involves ranking would tend to discourage more open ballot access, as people are more likely to honestly and accurately rank 2 or 3 people than they are to rank 10. If it can handle proportionality almost as well as single transferable vote, without additional complexity to the voter, it may actually be better fro ma practical standpoint.