Metalized coatings

Yesterday, the VP of Ops here asked one of those questions that he's
famous for asking. He wanted to know how long our EMI/RFI coating will
last. Our product is used in a controlled environment (medical device)
and the vendor (Acheson Industries) indicates that the coating will
last indefinitely but they don't have any data to support their claim
on our particular substrate (PC/ABS). I'm not particularly concerned
about the coating's performance but I have to write something up to
justify purchasing a bunch of other components "at risk". BTW, last
week the same person got all concerned about our powersupply's
reliability. Our expected product life is about 400 hours (this is the
time it will be used before it is replaced with something newer - it's
a give away reusable - our real MTBF is much higher than this). The
powersupply's MTBF is 600,000 hours. You get the picture.

So anyway, I've pulled the UL cert file for Acheson and can show that
the paint (SP-010) has been used with Polycarbonate and ABS ...

Basically, I'm going to write something for this VP to keep things
moving and I was wondering if anyone had suggestions beyond my
Lexan/Sicoflex defense.