Sounds very dangerous, I'll try it out in creative!
Well I'm planning on refitting my old mob system with soul cages so that the drop takes them out of spawning range to maximize uptime. I'll also have "rooms" that can have continual additions of auto-spawners set to whatever I need most of. All of this, including my cows are fed into a grinding room.
Another idea would be to have a way to have the autospawner stuff go elsewhere for soul shard upgrading purposes, but I am not too concerned about that. A couple tier 4-5 spawners should be more than enough mob essence. Cave spider, zombie and blaze tier 5 not hard to get.
Do auto-spawners spawn faster if they are supplied a greater per tick power supply or is the spawn rate constant, as so long as there is sufficient energy. I was considering the insertion of multiple auto-spawners dedicated to a single mob, as their drops I require the most. Someone suggested getting glowstone from witches + soul sand from sludge = netherrack. I can double my lava outputs, though I am not sure if I have the throughput for all that atm.
Still. Ideas, projects and stuff to burn through my blood sugar levels with vigour.