[Thomas Bertilsson]

I've done it, er, 370 times now to no ill effect. My spirals are completely clean, they load perfectly and do not contaminate the developer. Do you have any evidence to the contrary?

I do. When I used Photoflo 200 in the tank, next film developing session I would get these bubbles caught by the film reel, preventing the developer from getting to the film surface, rendering those spots basically undeveloped. It's just at the edge of the 120 film frames, but still irritating as it does affect a portion of the image area.
I did not use excessive amounts of wetting agent, and I do give the dev tank a good couple of whacks on a folded up towel on the counter top to attempt dislodging any such bubbles, and still had this occur. Once I stopped using Photoflo in the tank the problem persisted for a while until I bought a new tank and new reels, and the problem went away.