It's a good article, thanks.
As for the serious match rifle market (ie. that wanted recoilless, fixed barrels), despite using the brilliant Giss system, Diana's recoilless sidelever, the model 75, was delayed in production and 'missed the boat' for serious 10m shooters in a market already dominated by Anschutz and Feinwerkbau. The mod 75 came out around the same time as Walther's ground-breaking LGR single stroke pneumatic - a system that went on to dominate the '80s.
And when it caught up again with its SSP model 100 at the end of the 1980s, Diana had arguably missed the boat once again, since the Feinwerkbau, Walther and Anschutz SSPs were well established and PCPs would soon start to rule the 10m roost. At that point M&G gave up the ghost in the serious match rifle market.