This is a pretty interesting conversation so I'll throw in some of my thoughts with regards to mixing E fighting and angles fighting...
My E game, particularly in a 1v1 is used mostly to keep my opponent at arms reach (and usually when I recognize I'm about to be beat in the angles game by a negative-E opponent). Similar to a boxers jab, this provides you with separation to avoid being hit. When I say separation it doesn't mean out of guns range, it simply means denying your opponent a guns solution through a higher energy state or position gained by that higher energy state. There are many times when I'm in an E retention mode, while my opponent is hanging only 100 yds behind and below but lacks the speed & control authority to nose up in order to fire.
From here you use the time & separation to gain position before attacking again. Basically you're looking for a good opportunity to switch back to an angles fight, such as your opponent wing-dipping or slowly sliding out of position in a spiral climb. I rarely think in terms of bleeding out all my opponents E, I simply want to hold them at bay long enough to gain a better angle to pursue a shot with. If you're good at retaining E after switching to angles, you can miss a shot and rinse/repeat, especially if your move costs your target more E then it cost you in making the move.
In a many vs 1 fight, assuming you want to avoid extending, E & position is more important because you generally can't afford to scrub much E when switching to angles for a shot. You need to maintain your E advantage by either adding E faster then your opponents, or bleeding their E faster then you bleed yours. You have to weigh risk and reward, attempting to execute high G maneuvers only when it gives you a high probability of a kill. Although, killing quickly is arguably a better choice then killing slowly but maintaining E. It's very difficult to keep 3 or more cons from building their E unless they choose to bunch up tightly together and have to all break together when you attack. Try and stay close and above. The further away you are the easier it is for the cons to track you. Directly above with an E advantage you have the opportunity to drop in from any position on the clock and they can only force an equal angle merge by going vertical which can often lead them into hanging themselves in a difficult to control position. Be aggressive and smart, use your E to gain position and keep forcing them to react.
Lastly try and avoid being reversed, particularly by cannon birds. If your E differential is not sufficient to create separation quickly a good pilot will often offer a difficult/low aspect shot while rolling into your path in order to get a shot as you go by. You need be mindful of the direction you choose to extend in the event you miss your shot. Separate away from their lift line if possible to force a tracking rather then straight shot and cause them to scrub additional E in order to take it.
