I have a friend who just could not learn to fly his trainer. I put the buddy cord on my "Bingo" took him up three mistakes high and turned it over to him, he flew most of the tank out until I took over for the landing did not have to save him once.

He then told me that his trainer did not respond to small control inputs and when it did respond it was too much. I flew the trainer and sure enough it was much harder to fly than the Bingo.

I took his trainer home , cut the wing in half, decreased the dihedral and sealed the hinge line, he soloed the day after I returned his trainer. I think that a good low wing aircraft can be easier to fly than most trainers. The Sig 4*-x is very similar to the Bingo and I see no reason that it should not fly the same.