400, i think youre worrying about individual aspects too much. get a basic plan and work from there. im obviously less knowledgeable than many people on this site, probably most of them. but i ran a 12.3 in the 100 last year and i ran an 11.6 this year. i think all that because i made a decent plan and tried to stick with it as much as possible. try not to think too much and overperiodize. if you find that doing dannys program ACTUALLY has too much volume, then lower it. dont worry too much.
i believe in quality over quantity too, but were talking about TEMPO. worry about quality in your speed workouts and your SE, SE1, SE2 stuff. and you dont necesarily have to do tempo to stay in shape. im not exactly sure what to say next, so ill end there;)