Mike,

The OS .46AX is hard to beat! Yes, its more expensive but well worth the value.

I'm assuming that you most likely have a .40 on your trainer. Most trainers are not so great on takeoff performance, but fly pretty well once off the ground. What may help you is using a different prop that allows more RPM during the takeoff roll which should help takeoff performance. We need to know facts more like what engine and what prop you are presently using.

Maybe you can continue to use your current engine and put your money into your new setup.