> The position of non-voting shares is quite precarious I think, because a voting majority in the company can simply dilute shares and render the STAK-owned shares less valuable.

They could try that but if the STAK is properly administered then the notary public would insist on those new shares being paid in full into the company account. This particular trick is fairly well defended against in NL. But there are other ways in which a STAK certificate holder could be screwed out of their rightful share. The important thing to keep in mind here is that for every certificate there is a corresponding share with all of the right associated with that share, in that sense the situation of a certificate holder is not all that different form the situation that a minority shareholder in a company finds themself in with the major difference being that certificate holders themselves do not get to vote and that someone else gets to vote the block of shares in the STAK. If that person were to act against the interest of the certificate holders in any other capacity then they would open themselves up to a pretty good case for a legal challenge.