Could have SWORN I replied to this! lol.
Ovacue is different from the CBFM. It measures the electrolytes in your saliva (with the oral sensor) and in your CM (with the optional vaginal sensor.) It can predict ovulation up to 7 days in advance, and if you're using the vaginal sensor too, it can CONFIRM ovulation after!
It's great for anyone with an irregular cycle, because it doesn't measure your levels of anything against some predetermined number. It measures you against YOU, so it works for everyone.
It's more expensive than CBFM starting out, but since you don't have to buy sticks, it works out to be about the same price, I think. And not having to pee on anything makes it worth it to me. lol. Plus, you don't have to chart other things (temp, cm, etc.) because it does it all for you.
I got mine sent to me for review, but I would recommend it even if I'd bought it myself. It's an awesome thing to have! And you can use it for natural family planning also, which is fantastic.