I have good regular experience with 4 airports on the SH network.

MAD Fast Track security is good and works with BA Gold and puts Fast Track on the mobile BP.

At MAD, Fast Track boarding is quietly announced but isn't policed at all in my experience.

AMS doesn't show Fast Track on the BP. However it has a policed fast track queue for security but then when you get to the security machines it's a free for all (this is if you are using the high-numbered D gates). If you're at a normal D gate there is no Fast Track Security.

However AMS is very very good about managing Fast Track boarding and turns away those ineligible.

ARN prints Fast Track on the mobile BP. There is a fast track queue for security up to the BP check but then it's a free for all. There is a proper fast track with dedicated security machines for (I think) SAS and/or Star Alliance I think.

There is nominal priority boarding at ARN but again it doesn't seem to be very well policed.

DME - no Fast Track on BP from memory - but that is because you can't have a mobile BP there - the many many rubber stamps they feel the need to decorate your BP wouldn't work on your mobile! There is however a good Fast Track security route completely separate from the main security.

Boarding at DME - I don't remember. I am usually 3 sheets to the wind by this point