I'd like to see what David thinks, but I don't think a that-clause can be the object of than. Also, I'd use "to" after "preferable" (which does not work in example (d) as it clashes with "for you to...")
You can compare infinitival as well are gerundial clauses — the latter ones being indeed more formal:
e. His coming here is better than your going there.
f. His coming here is preferable to your going there.