Yeah definitely right now, I don't see making +11 or +12 certificates as worthwhile since it's much more efficient to use a +10 certificate and use hd carnium/bradium to get it to +11 and +12 certificates, so I can definitely see a decrease here.
But I also think the cost reduction should be based around the cost of using the hd ores. I'm not so good at math tho, so idk what that would be.