The characteristic you are describing between the Sierra-1 NrT and Sierra-2 with regard to male voices being more upfront has nothing to do with the choice of tweeter (at least not directly as you are presuming). The Sierra-1 NrT is a more "forward" sounding speaker than any other we offer. This was part of the plan for this speaker -- to make it more aggressive, more forward in its presentation, with more high frequency detail and energy than our standard Sierra-1.
This characteristic you describe is fully controlled by the crossover, it is a function of where the tweeter and woofer cross and the overall balance of energy throughout the speaker's bandwidth. We could design the Sierra-2 and make it just as forward or even more so than the Sierra-1 NrT. That particular type of sound, while appealing to you and others, is generally not as appealing to the majority -- who mostly prefer a more neutral balance in the soundpower response (all of the energy the speaker produces, both on- and off-axis)
That said, with regard to forwardness -- the Ribbon Towers and the Dome Towers are about the exact same. Both options are a bit more forward sounding than the Sierra-2, but less than the Sierra-1 NrT. I would describe the towers as being directly in the middle of the Sierra-2 and Sierra-1 NrT when it comes to forward presentation.
The question you need to ask yourself in deciding between the ribbon and dome for the towers is timbre accuracy, detail, and smoothness. For accurate timbre and detail in the upper mids and highs, the RAAL is unmatched. I *strongly* recommend it for audio bliss (as this is what you are trying to achieve) Our ratio of ribbons to domes is about 80% to 20% and this has nothing to do with home theater, but because of music. I would also say that 25% of our dome customers end up having us upgrade to the ribbons whereas we have only had one customer have us convert from ribbon towers to dome towers.
Now – if you prefer a more rock and roll, more aggressive top end response – something a bit brighter, a bit more HF energy into the room – (what most listeners are more used to listening too – unless they already own speakers with RAAL ribbons) – the dome towers are a good choice.