If it helps, the photo is what Mike and I run. The only way I've found to fix the twisting issue is to have two separate blocks that prevent the halyard from coming together. It's not a material choice problem.
Our finished length halyard is: 25' 3mm Ocean 3000 32' 5mm FSE Racing Sheet 12' 3mm Ocean 3000
The idea behind the tapered retrieval side is to reduce burns, friction, and weight on the kite. When dousing, you know to pop the tack line off when you hit the dyneema part.