To add- some counterweight on ailerons on our powered aerobats is always better than no counterweight .

The reason is an obvoius - the power pulses twist the plane and the ailerons always are the last thing to get the message
So they tend to remain still -which makes theSERVOS take upall the shock.
by counterweighting - the load on the servo is lessened.
Personally - I always counterweight ailerons - -my favorite is a tip balance -usually 1/4" wide and aprox 2" long- extending forward into the wing tip.
It is filled with lead.
the differece in balance is easily seen during engine run up - much les "ringing" in the ailerons.
One can argue the other effects - but the NET effect is less damage to the servo .
Response whilst flying is the same -
We really should be running interconnected - balanced ailerons but most of us are far too lazy to do this correctly .
On 40% areobats -I think it is a good idea.
Double bevel/single bevel - same thing - the total gap must be the same -
on our little planes hard to say if it makes any real difference - both are really lousy setups for a ful lscale plane .