Both.

Where it will really come into its own is in helping to stabilise the steady
state you have induced into any given 'corner' when you hit lumps, bumps and
ruts mid flight.

I would add though that if this is public roads you are talking about then
the need for a strut brace for cornering ability is really a little out of
scope.  Track use yes but for any real advantage on public roads then you
would have to be already exploring the handling limits of your car and this
might not be a good idea on a public road. :-)

Nick /////