My main issue with marmoset is safety. Unfortunately it's relatively easy to rip an object from marmoset viewer and that's why i don't use it anywhere in public for my commercial models. Sketchfab is much more secure, but there's very little chance that cgtrader will ever bring back support for it.
I wouldn't risk my models by uploading them to some obscure viewer, like that thing from autodesk, because it's unlikely that they would be any more secure than marmoset.