The difference between the NX .46 and the PTS in displacement is so small that you'll not notice.

Throw an 11x6 prop on the PTS and it comes into it's own in terms of power.

The flywheel helps smooth out idle problems, particularly when the engine is new, but once it has been run for a while, you can eliminate the flywheel without adverse effects.

IMHO the biggest thing to worry about with the PTS are the limiters.

You should REMOVE the blue collared limiters altogether ( not just pull the pins! ), then tighten up the clips to prevent the needles from "walking".

Once done, you'll have a nice and reliable engine.

You can also pull the baffle from the muffler to obtain a couple of hundred more RPM's ( more power ) too.