I have a .46LA in my Four Star 40, and I love that engine. It is very reliable and requires almost no fiddling with unless there has been a drastic change in temperature. During the summer, I would just start it and take off.

I have two ST's, a .40 and a .45. They put out a ton of power for the price. I haven't had any problems with either of them. They are very loud with the stock muffler, and they are on the heavy side, but I have never had to add weight to a tail.

If I were you, I'd fly the Nexstar with the .46LA. It will fly fine.