Good, we're on the same page, then.

I look at it like an SMA with some upward bias: after the price levels off at bottom an SMA will keep falling, whereas difficulty goes flat quicker (some miners keep mining even when somewhat unprofitable); when the price then goes up a level SMA will start turning up quickly whereas the difficulty lags a bit more (a few miners are willing to start when it's less-unprofitable, but most wait until the price goes high enough to make profit at a difficulty level).

In the end, it's just a lagging indicator of price, just with some extra factors thrown in ($/kW, MH/J, miners' inertia to start or stop mining, available MHps offline after a price drop, the $/MHps for new hardware) that aren't relevant to the fundamental value of a coin.

So for pricing purposes, how is it any more enlightening than an SMA45?