D9 is a plane with great speed, climb, (near)centerline mounted cannon and heavy machine gun firepower, amazing roll, dive,and good visibilty. Has only ONE big flaw in fact. Unfortunately, that flaw is being just about the worst turner in the game, you have to learn to work around that.
Like the other posters said, it is going to make you very vulnerable if you break out of a conservative game of high-speed passes to E-fight one guy while there are multiple bandits around you (but the same can be said about commiting to a turnfight with someone in a furball while flying a TnB plane). Look for anyone liable to bite on a rope though.
It is hard to see under the Dora's nose, and the plane does not turn well, and it will bleed alot of E trying to pull lead with a hi-g turn. Therefore, be leary of tracking shots, unless the opponent lets you well within 400 before he breaks and breaks predictably. On your standard more or less flat turn, look to set up a crossing snap shot instead, preferably after you've already made them break hard a couple of times to bleed off some speed. The biggest factor of difficulty in a snapshot is how much airspeed they cross your gunsight with.
Remember, that if they break DOWN constantly, you are going to have real trouble killing them until you are both close to the deck. If he gets you to take a shot nose down, you'll tend to end up overshooting beneath, leading to your energy advantage being cut deeply into. As a rule of thumb, always try to be fairly near level or nose up at the moment you fire, and pull into the vertical the second you miss/realize you have no gun solution. So if you are in a multiple bandit situation, remember to work the highest red guy there, and if he starts to do split-S down, instead of trying to equalize the E, he is probably just trying to suck drag you beneath friends and you should be patient, let them go and work the NEXT highest red guy.
One area I think I need to improve on in the 190 that you might also look at, is shooting from slightly longer ranges. I like to wait till point-blank, but I notice it can be difficult to pull into the vertical quickly and smoothly enough to avoid overshooting the flight path if they do a sudden break at -200 as you are quickly closing. So I have decided that I probably need to use the Dora's decent accuracy and ammo load to fire from further out, and either do damage or force them to maneuver while I still have time to react intelligently.
One more thing, a certain percentage of opponents in rides like N1Ks, HurrIIcs, LA7s, even some Spit drivers, will try to defend by using their turning ability to simply swap ends and HO everytime you close on your firing pass. Resist any frustration-born temptation HO, the radiator in your Dora goes out WAY too easy, you can avoid obvious HO attempts with a slightly skewed Immel and stay in their six quarter with E all day against such an approach. After all, the whole purpose of flying a high-speed E fighter as opposed to a TnB furballer is to kill AND survive to land, and that rules out HOs.
