Paper Cones in HiFi?

@gs5556 --

Not true at all. "Paper" tends to denote taking the cheap way out but is in fact a complicated mess of fibers, polymers, resins etc., engineered for light weight (has to react quickly), high rigidity (prevents deformation) and longevity. Paper's been a proven performer for decades - only recently have things like Kevlar and metal cones been introduced, and while they have advantages and disadvantages over paper, they alone do not make a speaker high end by virtue of their properties.

Very well put. 

If Magnesium was not offered, 
I'd have no choice but to go with paper. 
Thankfully Seas figured out how to get Magnesium to work,

http://www.seas.no/index.php?option=com_content&view=category&id=49&Itemid=246

Seas answer to Scanspeaks newest paper composite woofers which are indeed phenomenal..
But this NX001,  a  driver which  Troel Gravesen had some imput in the design, (Titanium voice coil etc), 
This NXE001 is something equal to Scanspeaks top midwoofers.
WOW factor off the charts.
Tempting for sure,, but I think I'm going to swap the bottom W18E001 for a  Magnesium W22 EX001.
Seas vs Scanpsek, 6 of 1 /half dozen the oher
But I am a  Seas devotee for life

https://www.youtube.com/watch?v=yVCZ8qDDStk

If you have a white paper (report), all materials sound good. Of course, that can be misconstrued as racist, so we have to say that whatever color cone paper you have is good, just to be equitable. And, to be inclusive we have to say that whatever material you use, it has to be accepted - no endorsed! Performance doesn’t matter; inclusivity is most important. The cone has to feel good about itself. ;)

I prefer high efficiency 15" woofers with paper cones (most if not all of this segment of drivers use paper cones anyway), preferably crossed not much higher than in the 500Hz vicinity - horn-loaded if possible or in duals (per channel) as direct radiators. In this frequency spectrum and sensitivity range the specific configuration would seem to dictate the material used.

Above that frequency compression drivers fitted to large horns are my choice, and mostly a variety of metal diaphragms are used in such drivers - apart from BMS/JBL ring radiator variants where polyester is used. Aluminum, titanium, magnesium, beryllium, plastic or paper compounds (the latter of which would be HF-limited) - I couldn't say which material in particular floats my boat. Some prefer aluminum here for its claimed tonal prowess (think Vitavox S2 as a prime example), others beryllium for its upper extension and overall relatively smooth response (Truextent diaphragms come to mind), the PA/cinema industry for years has preferred titanium for its durability, some domestic users favor non-metal materials for what they believe is less harsh/more natural sounding to their ears, etc. Inclusivity be damned; it's about preference, implementation and the specific use.