Original AP Tempos vs. Tempo III differences?

I presently own the Audio Physic Tempo (original 2 way/ 2 driver) model. I am considering the purchase of the Tempo III (3 driver model). My questions are, will the Tempo III offer significant improvement over the Originals? What differences can you articulate?

I use a Quad 909 amp to drive them.

Thank you in advance,