Does anybody know ALL the differences between the TD and the TD2? According to the company, the TD2 has a gear lever and a prop control, and otherwise is the same as the TD. However, there is a $1,000 increase in price, which the gear lever and prop control alone simply don't justify. In fact, why cannot someone purchase a TD and add a the prop control and gear activation lever as a separate box for $545 and save $455. Is there a difference, for example, in the computer performance?