RE: First low wing / Tail dragger, which do I buy?
While you're figuring out what to buy, take a few minutes and convert your LT-40 to a taildragger. I was going to say you won't need to buy anything but a tailwheel, but I forgot the new Sig's have the wire landing gear, not the old bent aluminum. You won't get exactally low wing aerobatic performance, but at least you'll get used to flying a taildragger with a plane you're already familiar with. Plus it's a fun afternoon project, and it's something different.
Andy