I went through this a while back when feeder fishing at long distances.
I tried all sorts of rigs and ended up using a free running rig.
The key in my opinion is simplicity.
Firstly i thread a snaplink swivel onto the mainline followed by 2 rubber beads then tie a micro loop to the end of the mainline and attach a swivel.
To this tiny loop I attach a micro swivel.
To the other end of this swivel i attach pre tied hooklengths.
The double bead creates a boom which prevents the hooklength wrapping around the mainline and also helps with the shock of casting heavy feeders at distance, although that is just an added bonus. The real positive is the boom effect.
The snaplink is in place to allow a quick change of feeder/bomb.
I then feather the cast down which also helps.
Retrieve should be controlled and not too hasty as this causes excess spin.
I now use this rig for all my feeder fishing.