I'm aware of the hugely inflated miles to secure an award seat on some dates against the stated minimums but Etihad says these are minimums, not fixed amounts.

However, the upgrade figures, as quoted on their website, are fixed and there is no mention of "minimum" for upgrades.

I don't doubt Etihad are underhand and duplicitous but legally, there is a huge difference between a fixed figure and a minimum figure.