Don't give up Brian, the AA carb is a good one and remote needles work great, you just need to make sure you have a good one. Your reference about going back to gas makes me think that your more comfortable with that style of carb, they are plainly two different animals. Most Nitro motors and carbs work differently, first the Nitro carb is designed to flow best at WOT, therefore they don't idle well, in fact when started and if set right are on the verge of loading up your engine until it's launched and you open it up. Depending on the engine and your set up you may need to throttle it up and down until it's launched to keep it clean and capable of launching. If you purchase a high quality aftermarket carb you will find them to be designed for the most part the same. As for your remote needle, there are a few that are good, the old cmdi style which work well but I find them to change a little bit too much for every click on the adjustment knob on your radio. The Ferrette needles with the OS needles I have found to be the best out there, the changes are finer, which I like, I make fewer mistakes on the fly.
Once you find your WOT sweet spot, I find that I adjust the needle very little, in testing in the morning I send it out fat, lean it in until it's crisp, bring it in, check the plug and that's it. If the day warms up a bunch, I may need to creep the needle a touch leaner but that's it.
I find how much I move the needle to be minimally from race to race. It sounds like you just haven't found that sweet spot yet, doing that is key to making a Nitro engine wail. This is all assuming your boat is set up correctly and you have the correct prop and pipe combo, if any of that is out of whack you can drive yourself batty trying to tune your engine.
Best advice I could give you would be to buddy up with a local Nitro tuner, they can really help you unravel the mystery. Best of luck to you Brian, don't give up, when it all comes together it's awesome!