Gas is non factor for me: if you wanna play you gotta pay. As for the the extra heat, this is the reason I bought a Honda: the reliability of their engines. These engines can take a good pounding. In my experience with Honda, the body and other mechanical things will wear out way before the engine. That being said, changing oil a little more regularly would be a good idea if you're constantly driving in D3. IDK, many people with manual transmissions probably are daily shifting at higher revs than an automatic in D3. It's not that big of a deal in my opinion. If you can afford the extra cost of gas, I say go crazy.