I think this whole "Complex engine start" discussion is a bit "pointless".
Especially about the warmup times.. I mean, during a battle such as BoB, dont you think that the planes on "alert 5" (In lack of a better description would have their engines running already?
Say, we get to the next mission in the campaign, and the mission is a scramble mission. Obviously a scramble will require you to get airborne asap, how stupid would it be if you and the rest of your flight/squadron had to warm up the engines for 5-7 minutes before takeoff?
In this clip, you can see the plane captains (or whatever they're called) start the engines before the pilots have strapped themselves into the cockpit! The engines would probably be "good to go" by the time they've taxied to the proper take-off point at the airfield.