Moving the Bix Festival form the last weekend in July will have multiple benefits.
1. As you say, smaller crowds and, consequently, easier to find hotel accommodations and to secure restaurant reservations.
2. The first weekend in August would come close to the anniversary of Bix's death. A good time to celebrate Bix's life.
3. Dissociate the Bix Festival from the Bix 7 race. The only relation that the race has with Bix is the name and the fact that it takes place in Davenport. Now that the organizers want to emphasize music, they turn to Elvis (!!!), instead of making use of the bands that are in Davenport for the Festival and play music associated wtith Bix.
A possible problem. How many people who come for the race, incidentally attend the Festival? If it is not a substantial number, this may not be a problem. Is there statistical information on this question?