RADIAL or RADIAL2
Apologies for the delay in replying. The 'RADIAL2' that you quote in your posting is in the introduction text of the M30 pro, not in the specification table.
As we see it, the current position is this -
Harbeth downloadable sales brochure shows (domestic, veneered) Monitor 30 as having a RADIAL cone.
The Harbeth website shows the Monitor 30 (domestic) as having a cone of RADIAL technology here
These are both correct. The M30 pro intro text is wrong and will be fixed.
The difference is apparent if you inspect the woofer. The RADIAL2 woofer has a larger, 'softer' radius where the surround leads into the half roll. This subtly improves cone to surround to chassis damping at the top end of the woofer's working range.
Alan A. Shaw
Harbeth Audio UK