I don't owl all that much during season. There are plenty of owls and crows and other aggravators around. All I need to do is be patient. However, I would suggest that owling can be done as well as any way with just your voice. All it takes is a little practice, you don't have to actually sound all that much like an owl as long as you get the rhythm correct.
If I need to locate gobblers in the morning, usually all I need to do is throw out an owl or two, either a "Who cooks for you, who cooks for you all" from a Barred Owl or a "Who Who" from a Great Horned Owl and the owls in the area will chime in. I've tried this all over. One night up on Lake Openango northern Ontario, I did this and got every owl going for miles. That, in turn, set off the wolves and we had a serenade going half the night. One tip: if there are Barred Owls in the neighborhood, use a Great Horned Owl call, and vice-versa. The two species don't like each other much, and if they hear an interloper, they'll sound off heartier. The trick here is to get the real owls to do your dirty work for you. If you get one angry at you, the whole neighborhood will respond, and then you can go silent and let the real owls do the heavy lifting.
BTW: When I use a crow call, I don't just Caw-Caw to attract a gobble, I use a wounded crow or fighting crow call to get the other crows going. That usually attracts crows, hawks, etc. Again, I'm using the real birds for the heavy lifting.