Hello,
I checked your settings and found that Limits/Cyclic Ring is very high.
I recommend to decrease this angle. I think decreasing to 10° can be enough.
Then I am not sure if you wish slow rotation rates, presently the model will be very slow.
If you need, please increase Rotation Rate, depending on your flying style.
Then I recommend to increase General/Flight Style to 8. For bigger model it can be easier to fly with this value. This can help with elevator too.
It is hard to tell if other values are good, because I can't see the model.
But there is nothing else strange.
There is almost no difference from 700 class models, so you do not have to worry something special is needed.
Very big difference is coming from used blades and servos in any case.
Spirit units are used on 800 class models and even bigger from around 2010 year
If you are using very low RPM then you have to make very good decision on used FBL blades and dampeners, these will cause the most issues. Because it will be very hard to tune and you will have to be very gentle on sticks.
Because you were using very high Cyclic angle then your tail was very likely unable to hold.
Model require certain RPM range in order that Tail can work properly.
If you use higher collective pitch and cyclic angle then demand for rudder is much bigger too. So at certain angles your tail can't be able to hold whatever you will set, especially with low RPM.
