however, the safe logoff button avoids emergency warp. in exchange for sitting in space without maneuvering or activating modules for 30 seconds, you disappear immediately when the time runs out. at least this was the mechanic a couple of years ago.
Still is. When doing sneaky stuff in enemy territory and they have all exits blocked the usual procedure is to cloak up until the combat timer runs out, then (after checking for hostile combat probes) de-cloak and start safe logoff.
If you're in something big and expensive (i.e. a black ops battleship), there's still a good chance you can get probed down and turned into a big fat juicy killmail before that timer expires.