Personally I like to stick to what I have read in the manuals but it is also important, in the name of good CRM, to listen to the other person and not to start a big discussion about trivial things.
Sometimes best handled by saying something like "really, that's interesting, I hadn't heard/realised that"....and then after the sector going away and double checking the FCOM....
(Actually that reminds me, I must go away and look up something I was told earlier today....
)