Realistically, the li-way and different marking scheme would only be used on cohorts in schools which reported the calculator errors. I don't think they'd change the marks of each and every Methods student.. However, with or without this li-way, I'd still be getting shit-all for Methods because I skipped most of those questions anyway..
I don't think there's a way to correctly work out which students used which calculator. It's unlikely that everyone in a school used the same calculator. If this "change" has been made, it will be an act that will affect every paper. The unfortunate thing is that for many, no actually change will be made and thus no benefit.
I thought it was rather simple, unless you got full marks, you will be affected.
If you didn't get the answers to the two questions, then your mark will be boosted from what it was previously as a percentage.
If you did get the answers to the two questions, then your mark will be lowered from what it was previously as a percentage.