Steve,
Sorry, if I offended you, I don't question your experience. Only I disagree with you observation. Until recently I was a Purchasing manager with a Top 100 PLC with over 9000 vehicles and other pieces of powered equipment. I've purchased and worked with (Degree in transport, member of various organisations such as IRTE) all sorts of diesel engines from 600 CC Lombardini's to 19 Litre Cummins and Deutz. Standard policy company wide after loads of testing fit "green filters" or cotton elements where applicable.
Talking to a Lucas Delphi agent re this post they wouldn't touch the pump on a car this age; the benefit is increased BHP, the loss is to the pump and accelerated wear of the engine. All Cotton filters should if correctly installed (regardless of make ) will give more BHp particular as there really a fit and forget item. If you want examples of documented examples I can supply. A Paper element starts to lose it's effectiveness after 2000 miles of UK roads, whereas the cotton element remains clean for about 10x longer . But as it was said in a film once "there is no right or wrong .only opinion"