I'm pretty sure that on the whole that would be a very good thing. Downvote visibility would certainly discourage dissent, which sucks. But I think the kinds of posts it would most strongly discourage are, in order, mean comments, stupid comments, and contentless (e.g. snide) comments -- which are exactly the things that have been dangerously proliferating recently.
And I don't even think it would much reduce the expression of minority opinion; there's a certain pride that comes with dissenting that makes it tolerable or even enjoyable when other people disagree with you. Whereas when you make a cheap joke, being able to see all the people who found it stupid or crass is a major buzzkill.