Done it in the past, never too regular though, but no breathup. Hypercapnia and lactic acid are safer than hypoxia while in the stairs. First time I tried it I kept going down and up for 40+ mins. My legs felt it for weeks afterwards...
Oh, and I go up 2 stairs each step, not sure if it's more or less demanding, I'm just used to climb stairs this way.
Scary story about the Jaw garywhiteeye, makes me think twice about trying it again.
