So....here's the thing:
I'm actually getting decent at flipturns. I screw a few of them up, but I always know what I did wrong. The ratio of good flips to bad flips keeps going up. But, because there are usually some bad flips along the way, I haven't set any PRs yet when using flips. I'm at 1:25 100m with (some bad) flips, vs 1:22 with decent open-turns. My 50m is hi-39sec vice hi-38sec.
However....
When flipping, of course we are not breathing through the approach, turn, and pushoff. This is not a problem for me in a hard 50m/100m. But in a hard 400m, I'm dying, Man!! The accumulation of not breathing for this period every 25m has me GASPING after 200m. I crave that open-turn breath.
Maybe I will learn to handle this, but I dunno.
Even if you flip well, should you sometimes do open turns because of the oxygen situation?