A couple things-
Why do anything "fancier" than what's required? If that opponent can be beaten by something as simple as a quick flat turn I'd just do it and be done. Quick, easy, and recover your SA as soon as you can... You don't need to impress your opponent by flying an aerobatic routine before you shoot him. I'd take the flat turn option if I was nearly set up for a shot, and could get guns on him to finish the fight very quickly. If it was likely to turn into a Lufberry though I wouldn't, or if our speeds were too much different.
If I had the speed I'd pull up over him, roll in and shoot him before he could recover E (and maybe even SA) from his flat turn. This is a "safer", "smarter" alternative. It allows you to maintain an E advantage, and quickly scan the skies as you go through your manuever (SA). You can apply pressure to him without getting overly fixated or committed, and that lets you notice the next guy coming in. Holding your E will also give you more options for this fight as well as the next.
If you try that initial flat turn and miss your shot on the spit, things can go sour pretty quickly. It's not so bad with the pony though. If you had the pony slow often the best option is to just pressure the heck out of him until he's dead. Don't let him get straightened out and fast again. Against the pony, I generally try to force him slow. Against the spit I'll avoid getting him too slow if it means I need to get slow with him. I'd rather fight fast against a fast spit than slow against a slow spit. I reverse that for ponies.
Once on the deck in a slow Lufberry against a spit, you're looking for trouble. You may be able to turn a smaller circle than him, but you won't be able to do it as quickly as him. The result will probably be him crawling around behind you, unless he foolishly decides to reverse his turn. Flaps will tighten your turn radius, but hurt your speed and turn rate. If I can't kill the spit within the first few seconds (3-4) in the flat turn I'm getting out of it. Do it early, before you're too slow.