Having never done it I don’t know quite how much control they have – Continuity’s comments up there suggest a few awkward moments have to be dealt with….!
Freefall terminal velocity is c 120mph and AFAIK these suits give you nearer 60 which means less of a wind to push against for control. But I guess the larger surface area of the suit gives back the control, but moving more slowly. I suspect the videos are edited to look as good as possible…
You’re essentially falling all the time, I don’t know if they can actually regain height, depends on your speed I suppose. I suspect the places they jump from and the routes they take are very well planned so they know there won’t be an unexpected higher bit…
Skydiving and BASE are pretty well understood in terms of the risks and how to manage them and as it goes, relatively safe – very few incidents as a % of jumps being done. As you say the margin for error is tiny in wingsuit.
Which is why I admire them. It takes balls to do that… and I can’t think of another sport where the limits of what man is capable of are being pushed so far right now…