I am sure some of these items have been touched upon in the thread so far. However my experience in learning 3D maneuvers has been the following
A neutral/slightly nose heavy plane is easier for me to 3D with than a tail heavy plane.
I struggled with hovering and torque rolls for months and months and set up the plane on the tail heavy side. I was finally convinced to move the CG forward on 2 of my planes
and keep trying to hover and torque roll. On one day I did about six flights inching the CG forward every time. Going from tail heavy to nose heavy. ( subsequently I do this on all my new planes to find the sweet spot) I found that once the CG got slightly nose heavy (and I mean slightly) the plane was more predictable and more responsive to tail inputs and my 3D skills started to improve
The reason for this is as follows.
When hovering with the correct throttle inputs (to low a throttle the plane falls off and nose heavy it falls quicker) the CG is not relevent to keeping the nose up as the prop is creating the lift (not the wings) and therefore other than the spinner 100% of the weight is behind the lift point (being the prop) . so keeping the nose up is a function of throttle to overcome the entire weight of the plane and in addition any drag created by surfaces moving and not CG location. Changing the cg will not keep the nose up only good throttle management will. (as well as the correct inputs with elevator and rudder)
The CG does make a difference on the reaction of the tail to input. The more tail heavy the plane is the more input you need to make the tail move as the tail has more mass or weight to move hence more input . think of pendulum, a heavy one takes more force to stop it moving and get it going the other way than a lighter on and essentially in a hover the prop is your pendulum pivot point) I was very skeptical but convinced after trying the gradual moves of the CG forward . The reason i think newbies "think" a plane is more reactive in a tail heavy configuration is they tend to not get the "instant" reaction on the tail surface in a hover and therefore add to much input and end up over controlling the surface and getting behind.
I have purchased about 4 planes from people learning to 3D and always find the CG to far back. Tail heavy is ok but just like anything else to much is not good.
I also find the "slight" nose heavy condition makes for better harriers and rolling harriers as the the nose wants to drop a little and adding throttle to compensate gives a really good constant forward momentum without having to constantly blip the throttle..
There are a lot of people that fly 3D very well with a tail heavy planes. I typically find that I have to have a lot more stick input when flying their plane to get a similiar manouver done and that around center their planes feel mushy. They always say my control surfaces are much more sensitive to them.
There is more than one way to solve the same problem and this is just my experience. I like the plane to react predictably and quickly with less stick input and found that when I moved the CG to "slightly" nose heavy my 3D skills improved exponentially. This may or may not work for you. But if you are struggling its worth a shot to try it.
just my 2c worth.