Jim C says:

Don't the go-fast guys use these systems to roll tack?

Not sure I'd call it a real roll tack, but it is referred to as a "gravity
dump", saves pumping time ;-)

snip instructions

Sounds like fun, but it might be hard on opened beers, sunbathers and galley
crockery.

It's most hard on those sailing around you, as your boat, with no increase in
wind strength, goes from 10 degrees of heel to 30 degrees of heel, then tacks
and appears more stable.
It's also fun to wait for someone to "drag race", and THEN load up water
ballast. Suddenly the boat springs 10 degrees or so more upright, and gains a
lot of speed.
Happy days!

Steve