Avistar too responsive? Isn't that what dual rates are for? Not having flown an LT40, I wouldn't know the difference but I'm sure it does handle a bit more slowly and land easier as it has only 75% the wing loading of an Avistar. But that makes it a heck of a second step to move to a low-wing tail dragger with the wing load equal to or greater than the Avistar. The LT40 wing loading is somewhat artificially low compared to every other trainer out there. Essentially what you're doing is moving a steep portion of the learning curve to between plane 1 and plane 2 rather than at plane 1. Which sounds like an excellent idea, unless the newbie gets bored with plane 1 before they've mastered all of the basics completely.
And Blackie, I suspect that if you had been running an OS .46 or similar (60%+ more horsepower than the junky little .40LA) the Avistar might have held your interest a bit longer, as well as providing a nicely broken in transplant engine for your second plane.