This is really cool! I guess the main competition in terms of similar purpose and guarantees is http://hyperdex.org/, although the add-on that enables transactions (quite critical...) is commercial.
2PC, at least in its usual forms, is not fool-proof: if failures happen in the "right" order then the whole txn gets blocked: it's actually proven to be equivalent to Paxos with F=0 (i.e. no ability to tolerate failure). On this point alone, GoshawkDB stands apart from anything that uses 2PC.