As opposed to remaining in manual flight and having to manage the aircraft, make all the callouts, commanding the PNF to make the Pan/Mayday call, recall engine out procedure, calling for the checklist? What in the hell are you trying to do, kill everyone? I guess you are special and like to do all of this crap and not turn the autopilot on but general consensus and common sense would demand the autopilot be turned on ASAP so you can manage this very stressful and busy event. As far as VNAV or level change is concerned, who the heck cares. It is very easy to figure that out when the AUTOPILOT IS ON. If the MCP altitude is set to the missed approach altitude, which is where it should be set after passing the final fix/ G/S capture, why would the aircraft descend? I guess anything can happen in an airplane but even that would be easier to catch IF THE AUTOPILOT WAS ON! I am all for keeping your flying skills sharp, after all it is a perishable skill, but your logic here is flawed.