Tracks can be hard, especially when you move onto ash. For general training you'll be fine with trainers, but if you're racing and you are building up to race fitness you'd need to use spikes to teach the legs what speed they are going to have to turn over at.
Only worth fussing about if you're racing.
I've not raced for a long time now, and the term 'drop' wasn't in use when I was (probably 12-14 year ago). I'd race roughly 4:00 1500m and training for this might include 8x300m reps at faster than race pace with 2 min recovery jogs (not static). Plus pace runs of 4000m (single rep) after a thorough warm up. This is in addition to the base training routine of distance runs and hill reps/tempo runs. Last session before a race would be something like 3 days before it and consist of 5x200m sprints or something like that.
By the time you've done nothing for 3 days your legs are itching to get going and you can explode a sprint start to get the head of a race without going into overload.
Fastest starts were usually in the XC mass events. Get a spot in the first ten of 200 runners within 400 metres of the start and you were among your peers to race the rest of the distance without the slower guys getting in the way!
Sorry, I've gone off topic and moved onto reminiscing now, how I miss running!