I must update P. Pilcher here:
"They have, to my knowledge, yet to have a "showdown" with an employer on behalf of their members."
The negotiators of the IPF have had a significant number of successful defences in industrial cases against companies for their members.
What Ag BIs says is, of course, correct, since BALPA have recognition in most companies by virtue of the membership percentage they have.
I personally have nothing but praise for the IPA/IPF and welcome a challenge to the 'encumbent'. Competition can be beneficial! Dual membership does not represent a significant extra expenditure and like a medical 'second opinion' can be useful.
I repeat - The IPF (not the IPA) CAN AND HAVE defended industrial cases on behalf of their members.