Doc -the slashed tip is a very old design trick -and properly used - works great.
It simply acts as dihedral
Most new pattern designs are very similar to stuff done over last 15 years - the large cowls don't really add anything- in the way of drag -tho they can screw up prop flow.
The best part is the increased torsional rigidity at front of the model
For those still using the shaker engines - this is a worthwhile - for an electric motor - not of any benefit.
However, the deep fuselages with increased forward lateral area, are good for the sequences and the lighter and stiffer the airframe , the better.
rudder hinge line sweep - a little does not hurt -
thrust line - matter of choice as the maneuvers stand - a bit above true wing C/L - good enough.
All of these, added together - tend to reduce stability - NOT making the plane unstable but making it more neutral.
The reduction in weight and improved thrust is critical
This allows the model to operate at lower angles of attack for any maneuvers.
Said differently, more constant AOA and speed - produces less difference in trim drag --which produces a plane that stays in the line desired. Up/Down etc..
And yes, we have tried all this for our own amazement .
Finally - nothing beats lots of proper practice time as the largest influence in flying pattern.