Only you can place a cpm value on your miles. Your example is a bit above 2 cpm and it is easy to higher awards/upgrade artios (but you should use a value you would pay not the face value of the airline). But 2+ cpm is not an uncommon vale.

But it really comes down to which you would rather party with miles or cash.
Hoarding miles is a bad idea because they can be devalued so easily.

For some with more miles than what they can use, why not use the miles and no worry about the the poor 0.8cpm evaluation.