Reversing when someone is on your six- I don't like the immel. If you are equal in speed, slower, or even only slightly faster than the bad guy he'll catch you and kill you. I love to see someone pull an immel in front of me, hehe.
I do more of a low yo-yo to the right or left. This allows me to have some more speed when I get my nose pointed back towards the guy with evil intent. I like to be lower than my opponent at the merge, but about equal in speed and bringing my nose up. This way I can merge more nose-up, while he merges nose-down. Not a big angle up or down, generally less than 45 degrees.
As I'm merging nose-up, I'm slowing, which tightens up my turn radius. He's speeding up as he merges nose down, which opens his turn radius. The combination of the two allows me to loop over onto his six in a slight dive to catch up, while he is still on his way back up.
The result is me on his six at about D600 and closing as he slows at the top. He dies when the counter shows D200.
If you immel with a guy on your six you'd better be faster than him or he'll catch you and be a real pain. If you are faster, and he's close eough behind you (D1.5K)and you read his E correctly, you can rope him. To do that just raise your nose slightly until you can't see the horizon over the cowl anymore. He won't see the horizon anymore either. Now, just continue to bring the nose up gradually until you are vertical. If you do it subtle enough he won't realize he's vertical until it's too late. If you pull up too rapidly you will give him a corner to cut across, and he'll kill you. The trick is to stay just out of gun range to keep him interested. Look tasty.
Done right, you'll both stall out at the top of the vertical, but you'll still be above him. As you nose back down you'll be on his six. Done even better, he'll stall while you still have enough speed to turn back down, either with rudder or by pulling the stick back for a back-flopping "loop". This way, while he flops D600 below you, you point your nose at him and blast him while he's helpless. I often find a notch or two of flaps will help me get my nose over the top and pointed back down. Those flaps need to be put back up RIGHT AWAY as you nose down though, or they'll mess up your shot. As you reach the top of your vertical (zoom climb) watch him out of your six view, and start your reversal as soon as you detect him flopping/stalling. This is a deadly devastating manuever when you figure it out. You'll die lots at first because you haven't read his E-state correctly, or pulled up to sharply allowing him to cut the corner on you.
It does sound like you're trying to out-turn your opponent with immels, etc. I don't like the immel for that, and I don't think the Dora is much of a turner. I think the tactics you are using are getting you killed. In the Dora you need to stay fast.
You can use your roll rate to your advantage by rolling left, say, and pulling slightly, and then rolling 180 degrees and pulling again (to the right)(scissors). If your opponent follows your lead, he won't be able to roll back right as fast as you, and so won't be able to follow you through your second or third break. You can use that to escape. Beware though. When you scissor you slow down. Generally you'll be trying to force the guy on your six out in front. I'd use it in a Dora to make him miss a shot and then extend out 3k for a new merge. (I wouldn't be caught in a Dora though). If you try it vs a better turner you'll be left slow and in dire trouble unless you kill him fast as he goes by. A slow Dora is 99/100's dead.
MtnMan