How are frequencies with the unit via the bracket going to be affected, would various frequencies be affected differently, or more/less than others. Or will the gain be increased over them all the same? Lastly, how does this compare to what would be achievable by boosting gain with DSP/PEQ on the standard mounted unit?
This is a somewhat complicated thing. The reality is that such a thing is technically a 4th order system. It could also be argued that its a 6th order. But, if we ignore the piston inside the Q10B...then its really a dual spring-mass-damper system...you get 2-orders per spring-mass-damper. The Q10B+lever itself, and the contact surface+seat. First the lever will flex on its own, and second the seat surface will flex. Both the lever and the seat surface will have resonant frequencies. The combined system will have a set of resonant peaks of varying heights that will be a function of how the lever and seat harmonics interact with each other. The closer the two resonances are to each other the worse these effects become. Attempting to describe the motion of a system like this, mathematically, quickly gets very complicated.
You can visualize this as a coil spring#1 connected damper#1, connected to a mass#1, connected to another spring#2, connected to another damper#2, connected to another mass#2. If you are holding onto one end of spring#1, and start to shake it up and down....the question you are asking me is "What does the mass#2 do?"
I'll be quite honest with you and tell you that this class of problems, 4th order (and above) Partial Differential Equations...rarely have symbolic solutions. In other words, we can't derive an equation for the motion of mass#2...we CAN do this for most 2nd order systems. So, typically we solve these problems numerically....ie, plot the response over time, and then take calculate the frequency response (amplitude and phase).
There are a number of variables that will impact a specific answer.
But, in general there are two cases, either the resonant frequencies are near the desired operating range of the transducer or not. If these resonances are well outside the desired operating range then the impact will be minimal. Its important to know that there are harmonics and sub-harmonics which will ALWAYS have an impact. So, in theory it will always be worse than a direct mount. But, from a practical point of view, it likely won't matter.
If that resonance is near (or worse IN) the operating range of the transducer, then YES, it absolutely will affect the response. As the driven frequency approaches a resonant peak, the perceived vibration will increase relative to the driven signal. So, a constant amplitude frequency sweep will be perceived as having the volume knob turned up and down at each peak.
How bad the effect is depends on the properties of the materials in question. The more elastic (technical definition, not lay) the material is, the less "damped" the response will be. Lower damping will cause a much higher peak, but more more narrow (Spring steel, etc). Higher damping will reduce the peak, and spread out the range of impact.
To a degree this can be "tuned out" using PEQ, in audio terms. However, such variation in amplitude output always has an inherent effect. That effect is a phase shift in the frequencies affected (compared to frequencies that are NOT attenuated)...which results in total harmonic distortion (THD...again in audio terms). In other words, there's no such thing as a free lunch.
This was my point earlier in the thread, when I said, it is always better to have a flat amplitude response in the seat than to try and compensate for resonances with PEQ. If you don't care about phase, then PEQ can work. But, if the phases between different transducers are different because of significant differences in PEQ then one tranducer's phase could get near 180* out from another and they would "cancel" each other out. So, instead of A+B you end up with A-B---we call that noise-canceling in other markets.
Anyway, that's a long way round to describe the design considerations for creating a lever based amplifier. That's not to say it CAN'T work. It clearly does for many people. The point is that careful consideration of the constraints and some analysis to ensure the system response is close to linear (free of large peaks) where you care, will provide an effective solution that amplifies the desired frequencies without any significantly undesirable effects. Or you can have a good intuition for these things, and just kinda make the right choices without really knowing "why"....and get "lucky".