I finally settled on purchasing a A-Tec - no one has a bad word about them, I know they are quiet and light. I spoke to my gun dealer, he has just come back and said that he can't get one - The old model isn't being shipped any more and the new ones are not available yet.
I have some money burning a hole in my pocket and I'm fed up with wearing ear plugs and disturbing the whole wood.
Where to now -
A Jet-z will be as quiet i believe but with the weight a couple of inches further forward, also not quite as universally liked as the A-Tec.
Jager Sporting Arms have some options but I can find no independant reviews or details size weight etc for their own moderators - I think one is called a Ranger - and they have a A-Tec copy - but it may be the same one. Has anyone put a meter on these.
A Pez T12 Scout is an option but not as quiet - the regular T12 will be too heavy for my rifle (Ruger m77 .308 - 3.9kg including scope).
Grrr - its taken ages to make a decision and now I have to start again.
Peter Jackson now holds the A-Tec importer status.
I have a Jager Arms Ranger on test - it works just as well as any other moderator ive used - its made from better quality materials (7 series aluminium) than the A-tec and is similar in size and uses K type baffles, which are all stainless steel. The one I have weighs 600 grammes.
I have bored out the baffles (with permission from the owner) to accomodate up to 338 calibre so the mod I have is not as quiet now as it was with smaller calibres before alteration.
Prior to being altered it was the same attenuation by my number 1 ear as the A-Tec / T8 / ASE Utra / PES - I dont have a sound meter, sorry.
I understand that pricewise, they are very competative.
I am not connected with Jager in business terms, but James (the owner of JSA) is a friend of mine - just in case anyone screams biased opinion...
The ultimate moderators in my own opinion are manufactured by Brugger and Thomet - but you are looking at circa £400, more weight and non servicable, sealed unit that requires returning to Thun in Switzerland for service every 10000 rounds.