Well I ordered an AlNiCo 8 magnet. I chose to not use the AlNiCo 5 because it gives the pickup a scooped mid range, and I just can't have that. it should be here Friday so When it comes and I get it installed I'll let you know how awesome it is. If I remember I'll record some demos of the sound before and after with the same amp settings.
From what I gather from the seymour duncan forums the pickup has sort of a sound between the Custom and Custom 5, It has a similar eq curve and the clarity of the Custom, with the warmth and big sound of the Custom 5. I repeatedly read people saying that it takes the best of the ceramic and alnico magnets. One comparison I really thought was interesting is that a lot of people say the Custom 8 is what the JB wants to be. With a smoother high range, and a better bottom end, but still has the good mid range. Really sounds like it's the pickup that I've been searching for so I hope it sounds good. *fingers crossed*