the empire sniper as stock does need its autotrigger timed a little but not as you are describing. it only needs adjusted so that the gun fires as the pump stroke reaches its rest position (as opposed to the gun firing before the bolt is fully forward). the gun is set perfectly to cock when the bolt is fully returned.
the problem is just what you would experience with any electro in the sense that if you are firing faster than the balls can fall then you are going to chop or fire an empty shot. and that is only down to the kind of hopper you use and nothing to do with the gun. fast hopper = consistent feeding = consistent shooting
I used a primo for my sniper and the quality of feed was rubbish, loads of blank shots even if it was nearly empty and one balling. also I thought it seemed huge and ugly!