Deidara is above Kakuzu in both speed and power.
Sasuke, Gaara, and everyone who fought Deidara was only ever able to tag him by taking him off-guard. Onoki had to work on his speed to match him. He is a speedster. CQC or long-range, Kakuzu is outmatched and can't tag him.
Also, C2's controlled missile defeated the Three-Tails and flipped the entire turtle island in one go, C3 could destroy a village, and C4 is invisible to the regular eye. Kakuzu doesn't have anything comparable. And yes, all of his hearts will probably get destroyed in one go.
The only argument I see for Kakuzu is elemental advantage through lightning style, but the doll that shoots lighting is not versatile and probably won't last the entire battle and will be taken down by controlled missiles.