Actually the diving DA merge works well in the MA to avoid a HO. I'll talk about this in terms of both the MA and DA to point out some similarities and differences.
When you dive under your opponent you gain speed (In the MA this forces your opponent to go neg G's to keep his nose on you... a difficult shot to track). In both the MA and the DA, once you're under and the distance/timing is right (just before the merge) you want to nose up toward your opponent (not a true nose to nose) forcing a high deflection angle slightly below his nose. This is almost impossible for a HOer to hit in the MA. In either case you're now bleeding speed while your opponent is nose down gaining speed. If he tries to track the shot he's also bleeding E.
Quick quiz: Who do you think will get over the top of an immelman first after this and who will have the tighter turn over the top? Correct, the guy who dove under partly because he's already losing speed and partly because he's already started on the immel while the other guy is still nose down.
Not only will he get over the top sooner but, now with less speed, he'll be able to go over the top, nose down then nose back up at the faster opponent coming over. This gains angles for the second time in the same move.
Note that the E states haven't significantly changed. The guy who dove under is managing his E better to gain angles.
Since I started using this merge in the MA I haven't been HO'd and I've been able to aquire peoples sixes a lot faster than I used to.
Grizz is right, you can't win an angles fight with lateral seperation in a similar plane match-up. There's no way to convert speed to angles without giving up E if you don't use the vertical and if you're the guy coming down you've already lost twice the vertical angle of the merge.
That's why all the top duelers use this merge.
[EDIT] Of course, I always lose in the first round.
