The new biostar lacks downvote from the beginning. However, I think a system with upvote only is fundamentally crippled. An upvote-only system encourages popularity but not correctness. Without downvote, the most voted question/answer is the most popular but may not be the best. We need downvote to balance the effect a little bit.
Several of users have proposed some minor modifications to downvote, such as greater penalty for a downvote, not displaying negative vote, only enabling downvote for users with enough reputations and displaying both numbers of upvotes/downvotes (in SO, you need 1000 reputation to see both numbers). I know downvote sometimes has side-effects, but we should not get rid of it without valuing its advantages.
I am aware that we have discussed downvote several times (e.g. here and here). It seems to me the consensus is to have downvote.
PS: I prefer not to poll on BioStar features. Each vote is associated with a different weight. A user familiar with SO/SE is more likely to have a comprehensive view on a BioStar feature than a new user. His/her opinions should be valued more. One may argue weight-associated voting also happens to common answers. That is true, but in that case, accepting a suboptimal answer only affects a tiny fraction of users who care about the question; others can still see all the answers anyway. On BioStar features, however, a wrong decision affects all users and users have no choice. Seeking the consensus among experienced users is a better approach than poll.
I am not sure how SO works with respect of downvotes, What is the overall score then if the downvotes are not displayed? Does that stay positive? Would the following be middle ground: an implementation of down-votes but with the property that
this is basically more of a display issue, the post score/reputation is actually negative only that is zero will be displayed until it gets into positive territory. It also affects sorting of course, posts with real zero will come before post with the "fake" zero score.
Istvan, reg. your 2nd point, I've never seen the reputation go below 1 on SO. For your 1st point, the score for a question, if it's negative, is displayed as such. Usually such questions gets closed and stays so unless the question has been edited and is better and someone votes it to be reopened. There is no penalty for one to down-vote a question. When one down-votes the answer, it's a -2. And with already 3 down-votes, the answer becomes flagged (for moderator's attention, iiuc). Part of becoming a learned member of the community is to know what one lacks (framing a question, expressing one's ideas/questions clearly, simply lacking knowledge in that field etc..) and it should be taken constructively when down-votes happen. The reason for down-votes on SO at least is "this question does not show research effort or is ambiguous and vague" or something like that. It doesn't say anything about the OP's intelligence. Just his effort.