RE: sig 4* 40
I have had the fourStar 40 and now have the fourStar 60. The four star 60 is a much better flying plane. I have built the kit version of both. With a kit You can easley do things like add 1/2 " to the rudder or move the canopy. The landing problems with the 60 are gone.
If there is any possibility that You will need another engine, go with the 60.
Make sure the tail weel is lined up stright or a very little to the left of the rudder.