I'll tell you what…Danny's training program is detail and very good. Some people would pay money for that type of detail.
You say that Danny's program lacks speed work, but in reality, he has power speed (4x40sled) work as early as OCT 30!! His GPP covers the aerobic base you need and also works on Accl. dev. It's really a great program!!!
On the other hand, the program you mentioned is somewhat of a hybrid GPP/SPP. The volumes of your long sprints are too little to develop the aerobic base and the intensity (up to 80%) is too high.
The idea for a 400m is to be able to have a high capacity to handle lactate. This far outweighs any .10/s that you can gain from a prolonged speed base.
I'm sure you are aware that the acceleration that you develop at 40m would be enough to PR. in the 400m, if you can maintain it. Danny's example is hitting it a both ends. Take a closer look and you will see that it's a great program. All you have to do is copy it as close as possible and have the confidence to stick with it :eureka: