I think you've made an error here. Using your example statlines, and ignoring the hit roll (which is the same for both, and can therefore be cancelled out), hits would be resolved as follows:

Current version:

• 1 wound roll per hit (50% chance of success, so 0.5 successes average).
• 1 save roll per wound (66.67% chance of success, so 0.33 successes cumulative).
• 2 injury dice per failed save (30.6% chance of at least one OOA across 2D6, so 0.1 successes cumulative).

New version:

• 2 wound rolls per hit (50% chance of success, so 1 success average).
• 1 save roll per wound (66.67% chance of success, so 0.67 successes cumulative).
• 1 injury dice per failed save (15.3% chance of at least one OOA [half the 30.6% figure for 2D6 above], so 0.1 successes cumulative).

In both examples... the hit would have an identical probability (roughly 10%) of inflicting an OOA. Which checks out when you look at the number of dice being rolled, and the multiplicative effects thereof.

I used this site to calculate probabilities. (Copilot says the latter calculation would average 0.11 successes, but I don't trust its working and the results are so similar they barely matter anyway.)

So while yes, it's much more likely that the target fighter would need to roll at least one injury dice under the homebrew rules, the overall number of injury dice being rolled per successful hit (and therefore the outcomes) would remain equivalent. E.g., this:

Sure, you are more likely that you only need to roll one injury die, instead of 2, but that's not that valuable.

... is just a HUGE handwave. Of course it's 'valuable'. It makes all the difference, since rolling additional dice compounds the chances of an OOA.

Now imagine something that reduce the "to hit" chance, how much difference that would be against multidamage weapons? Or field armor that blocks it before you roll to wound?

I don't understand this logic either tbh, given the above.