I am thinking about getting a Traeger, but am not limited to that brand. But I have questions....Which size is best for my family of five that occasionally cooks for 10 to 15 but I also cook Sous Vide? I love to do beer can chickens two to 3 at a time so I need that capacity. If I go up to one if the larger size models do the use a noticable amount more pellets? If I were to start out with a non digital model that is used, could I hook it to my sous vide module and would the ignition system react well to this?