I wasn't meaning to suggest it was (or should be) considered dangerous: just that supporting two concurrency models it that same time is a complication many would prefer not to bother with unless their application really needs the efficiency boost threading may offer within a single process on a single node. Unless you can justify working with both due to some measurable and significant efficiency gain or don't need multi-host scaling you go with the option you have to have (multiple processes).

Supporting both (multiple processes for multi-host scalability, threads for speeding up CPU intensive operations and such) might not be much more hassle, but it is at least some more hassle.