Every whole note should end with an eighth note leading into the next measures if it's a long hold. Watch mellophone range as you have them playing extremely high a lot. Some DCI players even struggle to maintain a good sound going that high. When writing drumline parts, try playing it and limit the amount of crossovers the players have to do especially at this speed, or in real time, you would get sloppy playing from a real life tenor player. I think you could add more melodies when the brass comes in possibly in horns and woodwinds. For the entire score, think about what will be heard of the field. At the very end, the splits in the trumpets are sloppy and will never be produced evenly and nicely in a full band. Spread the splits out across the Trumpet 1 and 2. A good rule of thumb is to have minimal individual part splits especially for marching band. For parts that you want to come out, put the part on the mellophones. They are the main driver when it comes to marching band.