Tim,

I haven't flown my Giles yet (been too busy from work to get my thumbs back from the winter), so take what I say with a grain of salt. I've been doing this with my other aerobatic aircraft. Also, this is my own opinion, for what I do. The final answer for you might be in what your level of tolerance is with this.

I would start out slightly nose heavy like you already have, and like the instructions and everything else has you do. This is required for stability. As you develop more familiarity with the aircraft, and work out the other bugs, sneak the C/G back a little at a time until you reach what I think of as neutral aerobatic balance. You will be losing some of the stability, but gaining aerobatic capabilities.

That is the point at which you can fly it upright, set your trim so that it flys with no control input like you normally do. Then invert it. With a neutral aerobatic balance, it will not take any down to hold altitude upside down. (It will be trimmed out both right side up, and inverted.) That is as rear as you want the C/G to go. It opens up a lot of different aerobatics possibilities (including 3D if the aircraft and pilot are capable).

Careful, as you get to this point, flying inverted can be tricky. You get used to holding down when you fly inverted. When you no longer have to hold down, it's a lot easier to get turned around on the elevator.

Landing also gets to be different, so make sure to work out the other bugs you get. Work to this point gradually, and you will probably slow the aircraft down more, but land with a little throttle on. (Somewhat like a Harrier landing approach).

Finally, as your wing loading goes up, you can't do this because of other things get in the way, such as a tendancy to tip stall. That's why people go to extraordinary lengths to get those 3D birds light rather than strong.

You will also end up flying it much slower. As you get slower, the controls get mushier. You almost need that to keep from overcontrolling your airplane. Full throttle becomes like full elevator. You just don't need it that much, or for that long.

It's a different kind of flying.

All of these things take getting used to, and may have you tuning some other things on your aircraft, and your flying. Another reason to work to that point gradually. You may also want to work some of this out with a less expensive, or other trial aircraft before you get to your Giles. You may also get to the point, as you work your C/G back that you decide you don't want to fly that way. That becomes your level of tolerance between aerobatics and stability, which is perfectly fine. Fly your aircraft the way you want to fly and don't let anyone else tell you differently.

Dan