Lots if issues identified. Some relevant, some grasping at straws to explain what we hear. We hear it, so there must be an explanation. I don't believe in magic, but I do hear things I don't know how to measure.
We pay all that money for fancy resistors so the primary parameter is, of all things, resistance. Non-inductive, non-Ferris, etc. And despite one popular WEB salesman, dipped or sand cast packaging makes no difference. The element, leads and caps do. Most higher quality resistors happen to be dipped but not necessary.
Ironic, we sometimes pay a pile for thicker wires in out inductors, and then put a resister in series with them. I have seem claimed high end crossover filters with L-R in series and foil or 12 gauge wire where just using a 24 gauge coil would actually be better. Same irony, LR in series and we pay for a low L resistor instead of measuring and designing on reality of the parts. Super low ESR caps with a series resistor? Low leakage with a parallel resister? Forgetting to look at DF or L!
Good thing, in my living room, even with my 60W amp, I am averaging less than two watts at pretty high levels in my speakers that I have measured, 87 dB, 1M on axis, outside on a ladder @ 1K.
Do not forget about "false" dynamics as most drivers are not in a feedback loop so they overshoot or undershoot depending on their Qes/Qms and the enclosure alignment damping effects. Many low efficiency systems have very high Q alignments trying to force a perceived deeper base response, read that "hump" or are forcibly eq'd to extend the bass and will have very poor dynamics. I target system Q's of about .6 as I find their dynamics better than the .8 or higher in many bookshelf speakers. Actual efficiency does not change as it is a function of the driver, not the alignment even though lower Q sounds louder.
Talking conventional dynamic drivers, usually, the smaller the driver the lower the efficiency. Usually, speaker systems with very flat responses have pretty severe filtering to achieve that flat response, BSC, Zobels, notches etc. All these can change the Q and can really effect the cone excursion pushing into mechanical compression. So, a 2-way 5 inch may at higher levels have not only more compression and bass distortion than an 8 inch 2 way for the same SPL, But it may have a lot easier time reaching the tweeter, so everything is a tradeoff. Or instead of that MT 5 inch, do an MTM, but now you get additional comb filtering issues to deal with but gain efficiency, lower bass harmonic distortion and likely higher perceived dynamics.
Do remember Paul Klipsch's original paper which basically set the rule: efficiency and distortion are inversely related. Of course, he ignored frequency domain and IM distortion so he built super efficient big horns to optimize the feature he considered most important. Everyone has their thing. None are wrong, none are correct. And yea, for decades it was hard to beat a couple LaScalla's and a DC300 for a band PA. Until THX, a lot of theaters still had a stack of VOT's. Dynamic? yes. Flat? heck no.
Also remember, the higher the volume, the less articulate our hearing and at some point, regardless of the efficiency, it is a wall of mush sound. And if you listen to those levels very much, maybe you need wider dynamic range than someone without so much damage to get any perception of dynamics. You, not the speaker.
In other words, a blanket statement like " high efficiency speakers are more dynamic" is false. Truth is it depends. Reality is the design choices that lead to a low efficiency speaker may, and again may, lead to a less dynamic sound.
