I have flown numerous LT-40's, and helped build two or three. It is the absolute best trainer yet designed, though not perfect. I also have a fully framed up and covered LT-25 that I have to finish installing the radio. It was a fun build, just takes a couple touches of sandpaper to remove the little ticks of balsa where the laser was shut off to hold the parts in the sheets. I'm installing a Super Tigre .29, but I'm at 3000 feet. It might be able to climb straight up with a 10 x 4 APC prop. Still, it is a Sig design and very well thought out.

You really can learn a lot building a Sig trainer kit. I helped a 10 year kid build an LT-40 around 1998 or so. A pretty long process that lasted months and months, but included flight training and building a 4-Star .40. The kid put about 200 flights on the LT-40, and after whacking the end of the wing going through through a gate, we even chopped off one bay on both ends of the wing to make it a bit higher wing loading. The kid when on to get his degree in mechanical engineering.