I recommend having more than one! Sometimes raspy sounds trigger. Other times high pitched sounds are the trigger. Rabbit sounds in a lot of places are used so heavily that bird sounds are more productive. Depending on the time of year, fawn distress can be your ticket to success, but even that can work at any time.
Closed reeds are great for their simplicity, but the versatility of an open reed will open up your calling tool box with more options. If you're still hung on just one tuning on a single reed, a raspy cottontail would be my suggestion. Good luck!