It looks like it's a toss-up on this. I was afraid that the 40 size would be a little small for the OS 70, and the 60 size would be a little big. However, for the style of flying we'd be planning to do with this plane, it looks like the 60 size would be a closer match.

As I said earlier, I'm not looking for unlimited vertical performance. Heck, my son asked for a GWS Slow Flyer for Christmas! He likes the slower flying planes instead of the rockets. Hopefully, the 60 will give me a happy medium.

Thanks for all the input.