Reducing it to the bare bones, the level of your terms and conditions are down to supply and demand, (which you cant do much about), and your ability to withdraw your services and go out on strike. This is only ever going to be possible with BALPA recognition; No other union is ever going to get the momentum amongst pilots to get membership levels sufficiently high, and no airline management is going to pay any more than lip-service to pilots demands unless they are filled with the fear of total operational collapse through a strike. Fine, save yourself your 1%, but you had better satisfy yourself with a salary a good 20%+ lower than the your contemporaries at a BALPA airline - A false economy, me thinks.
From reading the easyjet threads, I am worried that BALPA are still reluctant to rattle their sabre, even when membership levels are pushed above 50%; I think BALPAs worth will be demonstrated by their results at easy.
IPA are excellent at industry level lobbying, and for that I would recommend their membership, but I think it is a shame they set up the IPF. However, no airline pilot should be without BALPA membership, IMHO.