Actually if running considerable special bulk Vappy and Jellicent can come in on DM due to their healing moves and the power drop, so they are pretty safe switches to the Specs set. The issue is that they will have immense trouble with the ChestoRest DDer in particular due to even their status being shrugged off.
doesn't change the fact that Nattorei is a safer switch in into specs Kingdra. Also, the standard Vaporeon is always 2hko'd after SR if it comes into DM. taking an average 70% from a full power draco meteor. Yeah you can run specially defensive sets but:
1) you still take over 50% from DM with SR factored in and you're forced to use wish giving your opponent a free switch;
2) you lose the physical bulk required to wall Gyarados and other physical threats;
3) as you stated, if you mispredict and Kingrda is the DD or the mix variant you'll lose to outrage.