Well, the question was about how well does GM flyers do on upgrades on discounted fares. I think the answer it pretty good.
However, maybe a few terms to make clear. Do you mean "Discounted" or "Deeply discounted"? What Spiff is saying that "Deeply discounted fares" only receive .5 multiplier credit. K fares of higher receive at least one for one credit.
Personally, after their new changes in Dec., I am quite happy with the program but you might hear from a lot of people who don't like it. I think some of those are travelling from markets where Deeply discounted fares are available and they must purchase them by policy, and those who fly a lot of short segments. No, Mikey, I haven't forgot you.