Peering at public exchange authentication

[craig washington <craigwashington01 () hotmail com>]

Hello all,


Wondering your views or common practices for using authentication via BGP at public exchange locations.

Just for example, lets say you peer with 5 people in the TELX in Atlanta, do you require them to all use authentication 
for the BGP session?

Ive seem some use it and some not use it, is it just a preference?