honestly, if thats what you want to do, do it. I'm a firm believer in doing whatever helps you love running first, and whatever helps you run faster second... if you love it more, you'll never struggle with motivation.
For me, at the moment, what i'm loving is being able to completely relax on my easy runs, and still getting results, so that's why i'm trying to stick to it. It sounds like you are really loving getting flow on tracks, so do that!
Thanks Bart, your spot on there.