Late to the subwoofer party...
It seems the goal of adding subwoofers is to augment the main speakers in a manner the that is wholly indistinguishable from the mains. The trick is how to do this. There are a lot of pitfalls. I am not saying I am an expert in this field but I have experimented with several different subwoofer brands, the number of subwoofers in my room and types of integration. So I will offer some of my thoughts and experiences.
In my limited experience I have observed that not all subwoofers are created equal and as one of the posters above pointed out many of them are aimed squarely at the home theater market. The issue of getting a pair of great subwoofers that are going to perfectly integrate leads us to the main issue -- money. What we typically see is that someone has a pair of $100K+ speakers and wants to buy a $3k-$5k (or maybe less)subwoofer that has built in, off the shelf, plate amps and use cheap cables to connect it. This is quite a disparity. It is no wonder the result is often not satisfactory and the owner of the subs throws up their hands and just says "Subwoofers just don't work with my speakers!". As cmarin quoted his setup guru as saying, paraphrase: "this is going to take a lot of time and money if you want to get it right". If we want the great, deep bass, along with the other goodies that come along with it like soundstage and envelopment, then we have to start treating the bottom octave with some respect.
And once we have the perfect subwoofer there is the issue with proper setup. Even a perfect subwoofer not setup well is going to sound at best mediocre. Getting this part right is extremely challenging and requires a very good ear and a lot of experience. Just my opinion but If someone is trying to integrate a pair of subs with measurements only then it is not going to end well. I posted in another thread about how integrating a woofer affected how an oboe solo sounded. When not properly aligned (I am talking microseconds off here) the oboe sounded quite bad. When the woofer was correctly aligned the oboe sounded phenomenal. There is no way I know of to detect this with our current measurement capability.
The Rockports certainly have articulate bass. Matching that is not trivial. It just depends on how badly one wants it.
The subs I personally want are from a company called PureLow. Look them up. Not cheap but integrating a pair of these would be pure bliss with any speaker. Unfortunately, getting a pair with the required matching amplifier, cables and crossover is going to cost almost as much as a pair of mains.
I agree wwith you and like everything else in audio a DAC is not a DAC, A cartridge is not just a Cartridge and a Sub is not just a sub. They all "do " some of the same things but how they do that is not equal. I was at Carlos's home with Stirling and I also thought the subs he had were a distraction not a positive thing. This however does not mean that something different would not work, in fact quite the opposite.
The first sub that I have b
een crazy about is the one in the pictures. Cheap NO, small NO, relatively easy to get great performance YES. That is not saying its plop and play but it can and will integrate with the room and other speakers. Todd I know you have horns , I have no experience in that area so I am going to plead the 5th there however Rockport is not that dissimilar in the way it works or sounds from mine, or a Stenheim and a few others I have listened to a bunch.I have not done a set of Lyra's or Orion's but I am very confident that it can be done and done really well. Oliver is a very sharp young man with a ton of knowledge and expertise, both musically and scientifically. Its why I got involved with the brand. Josh Clarke is a friend and I really like the speakers they make and under different circumstance would love to represent them. My business is too small to sell those two brands.
By the way the nice thing is these subs are easy to play around with and can do it from you listening position , so you can do it alone and there are 4 presets if you are one of those that wants to screw around with different settings for different things. It took me a while but once they were settled in I adjusted one at a time until I was happy. Then listened for a while ( two weeks) with out touching anything and at last one slight change, which was probably full break in to turn them down a smidge.
My client had a six pack and sold it after 3 months and swore no more subs. He now has two of the ones in the picture with his Noblesse and could not stop praising the result.