I have a 64 GB Mac with SSD and managed to trick it to use true hibernation (Apple does not want you to know it but you can still achieve true hibernation by enabling disk encryption (FileVault™) and forcing key material erasure from MEM on standby with `sudo pmset -a DestroyFVKeyOnStandBy 1`). I just timed it and bootup from hibernation to UI took 25 seconds, out of which maybe 5 seconds were taken by inputtting the encryption password.

Certainly not a show-stopper, if this means not accidentally killing my €2k+ laptop because it decides to randomly wake up in my bag.