I have worked with their best 6.5" models. They are well made and do a lot well, but like all things there are compromises especially when trying to build one driver that does everything well.
For instance covering bass ranges well typically means a thicker and stiffer cone (more moving mass), longer X-Max capabilities, and a motor design that will maintain linearity over a long range. All of those things compromise performance higher up in frequency. The high moving mass typically means slow or longer settling times. So a woofer playing down low and playing it hard (even cleanly) is going to compromise midrange and higher ranges. This is why we have three way designs.
Our drivers of the same size, have a more limited X-Max, and use a lighter weight cone and have a lighter moving mass. This means they settle faster, sound cleaner, and have a better overall sound. However they will not do as well playing down low.
I am experiencing what you are describing right now. The Scan-Speak 8545 in my Merlin VSM plays low... makes great bass... what you did with the speaker made it sound better than it ever has. As I think you know, as I have shared with Hobbs... just because I could, I put the M165NQ driver into the VSM. The baffle width between it and the NX-Studio is the same, the efficiency between the drivers is he same, etc. It was worth a shot to learn something, and boy have I learned something. The midrange clarity from the M165NQ is superior to the SS 8545 driver; however, the M165NQ does not play as low - just like you referenced in your example. But the thing is, in the ported enclosure of the VSM (which I have not seen anyone else try / reference M165NQ in a ported application), the bass from the M165NQ is not "weak". It makes good bass, although not as low as the 8545.
And then the choice between the 2... well, I have / can buy more low end for a speaker via a sub. I cannot make the 8545 have the midrange clarity of the M165NQ. For me, I'll take the clarity and add some low end, if needed. What I am experiencing is why I'm bothering to even do it... to actually hear / experience the difference and more fully understand the "Why?". There is no doubt in my mind the strategy you're using is the way to go... use the proper tool for the job whether "the job" is midrange or low end. This little test has also helped me hear and anticipate the clarity I'd experience with the Studio, Otica, or NX-Treme in my room, with my gear. It's one thing to hear your NX-Treme in your room / your gear, but now the experience has really been driven home.
I'll add this though, I think a lot of people could be very pleased with the M165NQ in a proper, floorstanding, ported enclosure. Not everyone needs / wants response well into 20Hz. People have different recipes for what their definition of "Fun" is, and I think by providing different options, but also educating the customer about what the "best" is, people can make choices that are best for their space, budget, goals. As they learn / experience more, they can move up the line. I'm going to continue playing with the enclosure of the VSM to get the volume / port alignment exactly to spec Hobbs provided for the M165NQ in ported cabinet (if there is enough space inside the VSM, which I don't know for sure yet).
Bottom line, I'm experiencing your strategy for why the drivers are designed the way they are, and why the choices are made. I am also hearing that the M165NQ is an absolutely exceptional driver. My ears are telling me your entire strategy is right, but you already know that.
