When it comes to a slackline I'll venture to guess most people think about walking the length of the line,
like Cigar Guy here...
Walking the line there's definitely some lateral balancing going on, but it's quite different from skiing, as
there are no turn forces to contend with.
However, when standing across the line there tend to be a lot of rapid accelerations/decelerations courtesy
of its inherently wobbly nature. The type of fore/aft balancing that takes place seems quite similar to what
happens when skiing, for example, sticky spring slush. And although personally I have no experience (yet)
hucking anything, when perpendicular on/to the line I find myself doing "rolling down the windows" type
motions I see skiers in films doing when they're trying to stay balanced in the air.
It remains to be seen how much any of this learned balance will be beneficial once actually back on skis,
but it won't be long now. Heh heh. ;-)