I believe the main reason the plastic diff halves used "keyed" diff rings is simply because any slip between these components and the diff would soon melt.
You don't have that problem with steel diff halves.
However, i used the standard diff rings with the plastic diff halves and it was fine - but this was for the front diff, which is under less stress than the rear diff.
If I try the TA05 plastic diff halves in the back it will only be with the "keyed" diff rings.
I personally wouldn't recommend using the alloy diff halves either - having used them in both the 415MSX and Evo5 - they wore quite badly if you didn't replace the plastic blades very often. I also think the plastic blades wouldn't hold up too well in mod.
Thanks for updating the setup sheet Jimmy
