That’s for artists to decide. But I think it’s worth noting the comment I made in another topic;
If fans have made the effort to find to find an artists page on an indy platform, and pay them money, they’re probably not an attacker who needs to be defended against. In the unlikely event they pay money to be able to share the special extras with people who haven’t, that won’t stop the people inclined to pay from doing so anyway.
The main thing that motivates digital pirates is a desire to make information and culture available to everyone, regardless of ability to pay. So I highly recommend the approach Cory Doctorow takes with audio versions of his books. Free the work for everyone, under a CC license, once a declared funding goal is reached (eg costs are covered, or costs+margin for the artist).