Rel vs the world


So whenever you look for subwoofer recommendations for 2 channel hifi, one name keeps dominating the conversation.. rel. And the flagship no 25 is seen as the ultimate subwoofer by many. My question is, has anyone compared well made but more affordable subwoofers (JTR, PSA, Rhythmik) to rel subwoofers (especially no 25) and go equally good or better results with the more affordable subwoofers?
Also thoughts on effects of cone material on sound in subwoofers? I am very interested in the choice of using carbon fiber cones on speakers like Alon in Magicos and Michael Borresen in his speakers. When I saw this in the rel no 25 I wondered if that was one of the reasons people were impressed with its performance. I found this article that Tom from PSA sent me pretty interesting.
"Myth: Cone Material Affects the "Timbre" of Subwoofers

At low frequencies, in the bass region below 125Hz, the cone material has no effect on the sound. If it did it would only be because of peripheral side effects such as a large change in the moving mass of the driver, or a cone who's strength and stiffness is deficient for the application allowing a lot of flex and distortion. A subwoofers cone or diaphragm should be stiff enough to not flex appreciably even when under heavy air loads. Any sufficiently stiff subwoofer cone would have resonances or breakup modes which are well beyond the bass range and should be inaudible with a typical low pass filter applied. If we have 3 identical sub drivers with different cone materials, one with an aluminum cone, one with a carbon fiber cone and another with a pressed paper cone and all are adequately stiff and the total moving mass of the driver is within a few percent of each other they will be indistinguishable from each other in a blind listening test.

The main take away here is that subwoofer cone material choice is primarily a consideration of strength/stiffness/durability/cosmetics/cost and weight. Sound is not one of those considerations.
"https://data-bass.com/#/articles/5cbf5e7357f7140004d6d0ec?_k=o4xuea


smodtactical
quality of subs matters, but in a multiple array they do not need to all be identical
Don’t confuse timbre with speed and impact. I’ve never considered nor experienced cone materials to color the sound in the 1000+ subwoofers I’ve bought, built (cabinets) & installed. There is a profound effect on the quality of sound reproduction however. Dynamics, transients, etc. The non distorted speed of a sub directly relates to how well it will not just integrate but seamlessly blend and disappear. 
For all their exotic terms quality mfg’s are all really just trying to use the lightest material, that will not flex/warp, under the Enormous loads it is subjected to when creating atmospheric pressures. 
Then as you x/o point increases timing becomes more apparent. REL places significant emphasis on their hi level input quality & super low latency. And I have to agree it does work very well. Other mfg’s do not place such emphasis here and this does set Rel apart from the pack. 
I personally own REL’s. They deliver on their promises.

I do not have experience with the brands stated in the OP so cannot give direct experience there. 
Next on my list, and I’m extremely keen to build & hear, are the GR Research Servo Subs. 
Why? The tech in those (amp incl.) also set them apart from the pack. I have read up a-lot on those subs and I couldn’t tell you what the cone material(s) are... irellevant. What’s relevant is they’ve clearly selected materials that match their desired outcome. Very fast bass response with inaudible distortion. 
Ppl mix timbre up with transients & distortion/speed & mud. 
I have tried few top tier subs and nothing came close to matching REL’s agility and uncanny ability to gel with your main speakers. They do deliver on the promise!

I have not tried No. 25 but a pair of Carbon Limited in my 15’ D x 30’ W delivers ample high quality bass.