It may also have an effect on how far your axle moves forward/backward on extension/compression <- this has an effect on pinion angle throughout susp movement and how much slip you use in your driveshaft. It will probably soak up bumps better, but brake dive may be a little more apparent.

I think with my shackles forward I will still end up with the shackle-side spring eye slightly above the fixed-end eye, but I think that may end up a good thing--caster might be better, axle may not move forward/backwards as much as susp moves, etc.

But, it is probably something that demands more attention on a street-driven rig than on a trail only rig. <img src="/forums/images/graemlins/cheers.gif" alt="" />