Barefoot is much easier to get used to on rubberized tracks than running in spikes and much easier on your feet and legs.
When I was running the 200 and 400 they were usually in spikes, however I ran 200's in 23 sometimes barefoot in practice. The main thing is that your feet are not slipping. Most rubberized tracks are very good for running barefoot, unless it's a crappy track with a lot of grit on the surface that would slip and also tear up the feet, which has happened to me. Definitely wear shoes if that's the case but that's rare and you could tell warming up.
I'd say if you're running faster than 60s 400 pace then spikes can be desirable, but anything slower then that and barefoot gains the advantage by far. There is nothing on your feet so of course it is faster, as long as your feet are not slipping. I have always run 5000's and 10000's barefoot on good tracks, and the occasional 800 and 1500 as well.
Some of the Kenyans have run close to 8 flat steeplechases barefoot. Bruce Tullah and some of the other English runners used to race frequently on dirt and even cinder tracks. I don't know how they did it on cinders! Ryun used to wear flats on a cinder track for most of his workouts in high school. IMO flats slip a lot on cinders so I would always wear spikes on that type of surface.
You can always try different ways and to see what works best for you.