That's an interesting article Mark. For me the comment about the performance of the unit away from the sea is the key - The performance enhancement of the salt water diminishes rapidly as we move out or away from the “fresnel zone”
Personally I would rather carry 4 pieces of wire to give me 4 elevated radials rather than a GTU which would weigh more and require adjustment on site. To date I have used my vertical over a variety of ground types including made up ground (Hensbarrow Downs) without the need to spend time adjusting the antenna. However I like the idea for beach sites as it removes potential trip hazards and may well consider one for my /A site up in Northumberland which has miles of unspoilt and largely unoccupied beach close by.
Thanks for bringing this to our attention.
73, Gerald G4OIG