I agree with you that there are cases in which Dropbox might pick up false positives. I think the DMCA should be updated with harsher penalties for improper takedown requests ("copyfraud"). Still, the policy Dropbox has seems pretty reasonable. And you can always choose to encrypt your files locally or even not use Dropbox. After all, it's a company competing in a relatively free market. But I think for most people Dropbox is a pretty good choice and this takedown policy shouldn't be a reason for them to stop using it.