I was under the impression the rubber diaphragm in the OEM was the one that leaked.Bill @Badger5 reckons the diaphram oem (other diaphram makes available) is the one to have as all piston style ones bleed or leak - What i'm not sure of is the context - as standard/map 1 etc. I would like to see some definitive evidence from a sheer curiosity point of view.
The Forge 008 on my old stage 1 AUQ (now owned by my mum) is coming up to its 6th birthday. Never leaked never needed a service.