Hello there Speedbird,
I'm most impressed with the debate you've stimulated on this topic. I think all the replies have been well written, mature, and carefully considered. Exactly, IMHO the sort of thing that makes this website worthwhile.
I'm saddened to hear that it took BALPA so long to respond to your enquiry. In my career, I have found them to be frustrating at times, I even left them once. I do admit though that the career I've enjoyed thus far with a good airline has been good largely because of BALPA. The support of BALPA by our pilots has been crucial in establishing and maintaining a decent working life.
I commended BALPA to you largely for the legal representation it could ultimately provide if you suffer a really bad day. For me that underpins membership. I still believe it to be the best.
I'm sure you have sought the best in your training, aspire to be the best you can be, and want ultimately to work in the best possible environment. You certainly won't want to end up in some frightful sweat shop company, with poor standards, poor conditions, and poor working relations.
For me, anything less than BALPA is second best.
I think that you had made your mind up before your original post. Your comment that BALPA took 2 weeks to reply after all predates your original post of 11 days ago. I'm sorry then, that I and all the others posting in favour of BALPA have not carried this debate in your case. No matter, I shall be gracious in defeat and wish you well.
Good luck to you, and remember - you can always change your mind!