Why can't you do the math to figure it out? Play around and find some solid, predictable rates, then do some math and see if they're not almost equal in cost like I expect they will be.
And, this makes no fucking sense whatsoever. Idiots abound.Either way, the click fraud is going to effect you though. With CPM you might not actually pay for the fraudulent clicks but they will still artificially lower your CPC to the point where you THINK you're profitable. This can throw off your entire campaign and end up with you consistently losing a ton of money and not really understanding why.
I've started to pull away from FB advertising completely until this all gets resolved. Too many headaches trying to analyze numbers and having to take that extra "fraud" variable into account.