Whoa Speedbird and Roman!
Consider an alternative view. Dissociate the industrial side of things and just think about this. BALPA have access through IFALPA to the best representation in probably every country in the world.
The IPA may have a fabulous policy to protect you, but it is only so much money, and can it add the value that BALPA can provide through it's work on technical committees, finding expert witnesses etc., association with local unions and their own expertise.
Will any insurer look to fund you without keeping one eye on the bill, they are in it to make money after all. They may just go ahead and cut a deal with the prosecution. Their loss-adjusters will want them to. Will it be in your best interests?
In an accident you need the best help immediately. I know of a case where after an accident, the 2 BALPA members involved were interred by the local police, and forced without representation to make statements whilst dazed and confused. BALPA, through IFALPA got the best local aviation lawyer on the case immedaitely. He arrived by exec jet from the capital, and immediately got the 2 pilots released from custody, and had their statements dismissed, and torn up. They both returned to flying shortly afterwards.
The world is fast making litigation an Olympic sport. After an accident, everyone will range themselves against you. Will the insurer get the best lawyer, or will it go for the low-cost option? The manufacturer, the airline, the airport, will all want you blamed. It will be their prime interest. For me, BALPA at a time like that add value to your case through their expertise.
Now all you PPRUNERs out there can get hot and bothered, sound off and tell me what a twit I am, vent your spleens on this thread etc. Take a pop at me by all means, but for me it is simple.
With my 20,000th hour shortly to appear in my logbook whilst I do my level best to ensure that I shall never need BALPA, in the event that I do, I believe they offer the BEST possible back-up. For goodness sakes you even get a tax break on your subs!
If you are comfortable with the IPA, then fine. If you want tried and tested, go for BALPA, I commend them to you!