@jk - I had thought about that too, but then I would be faced with a graphics / sound / whatever card that needs securing again somehow. The PCI cards are obviously not build to be outside a case, the only other thing I can think of doing in some kind of brace. I'll try and mock one up and add it later.
@MasterArcade - I will have to take your word for that my friend! Looks like you know a little more than me about transfer rated etc., although I do appreciate the dropoff you mentioned in signal quality. I'd looked into the bench too, but I don't know if this will enable things to be secure as it is just a testing rig.
Thanks chaps -- any more thoughts?