For an iterresting effect on the pattern plane... try the 12.25 X 3.75 there too. Up lines become easier to hold. Down lnes don't gain as much speed. You can almost go through the whole pattern without touching the throttle.

I'm not familiar with the Zen specificly... but the .46 FX using the 12/25 X 3.75 can pull up to 9 lbs vertical, practically unlimited. With a 4*40, (at a bit under 5 lbs...) I was pulling continous inside-outside vertical 8's as long as I wanted at 2/3 throttle.