I have in one of my worlds a turtle based farm with multiple tier 5 soul shards dropping mobs into a big mystcraft portal which teleports them into a 1x1 shaft to a 18 meter drop (so they low hp left) then 4 turtles at the bottom around the shaft killing them and collecting the drops with filters+timer underneath them to suck everything into my sorting system. There's also a transposer in the tile the mobs land on, so if the turtles don't pick something up it gets sucked in anyway.
For now i use skelleton and zombie shards (because they are easy to get, thanks TC3) but my spider shard is almost tier 5 so i'll add them soon too, not sure how well will it work with a 1x1 shaft (will the spiders suffocate?) and thinking about making a blaze one too (gravity doesn't work on them i think, so i'll have to do it somehow differently).
You can use relays instead and have the turtles output the loot directly, but it seems to slow down the killing process (there's a forced sleep when moving items or something like that).