I am sorry the Tempest did not work out well for you, but like Erich said, there are a couple hundred of them out there and I have received a lot of very positive feedback on them. There was another speaker shoot-out a few months ago and the Tempest was raved about for how it stacked up against some very expensive speakers. It was considered the best value for the money in the group.
I voiced the Tempest with a lot of vocal music using my Kairos and Continuums as references for midrange balance. The Kairos is especially flat through this region. I felt that the Tempest had an excellent midrange balance and I have commented before that I could have lived long-term with the Tempest as my speakers. I never noticed any excessive chestiness in the midrange.
I have attached my quasi-anechoic response of the Tempest. Although the response is bit tipped-down, there is no hole in the upper mid / lower treble region. (I was unaware at the time I took this measurement that my mic had gone out of calibration above 10khz. That has been corrected, but the reality is that the Tempest drops off a little by 20khz). The 98 dB rating is in the woofer range with the tweeter down a dB or two over its range.
So, what could be causing the dip that is shown? Well, since this is two-way speaker the measurement axis makes a big difference. My axis was directly in line with the throat of the waveguide. Since it is a large speaker, too close of a distance can cause issues (but 30" should be OK). Like all two-way speakers there will be lobing and nulls on some axis at different distances. The other possibility is that the tweeter is reversed in polarity from intended. The crossover is not symmetrical so a reversed polarity will cause a dip above the crossover region. I would try reversing the connection of the woofer or tweeter and checking again. Beyond this, I am not sure exactly what may be off. I hope it gets resolved.