Well, I ended up with the Kubota blades.
I did look at both options for my mower.
(They were coded, not named?)
The 'lower' option blade had a higher, 'sharper' angle wing, by about double.
The 'higher' option blade was a lower wing.
We came to the conclusion that the lower option, higher wing created more wind to contribute to exiting the mower quicker.
And of course, the higher option, lower wing created less wind, so cuts stayed in the mower longer - thus mulching!
And they were 30 degree edge.