Yes my experience with lipid deposits (Lily has one) is that they are harmless, but clearly while they may be, they aren't always -- lots of eye specialist vet sites say otherwise. Always good to keep a casual eye on them to make sure there's nothing to worry about. I was told they are almost always nothing to worry about but that is not the same as 'never'.
I don't agree on pain though. I have three that wouldn't be much bothered by a hair in a comb! And others that would -- but that kind of pain is very different to far more serious pain which they simply just tolerate. I know the neurologists who work with this breed say the same, and have in some of the SM seminars. My dog that has the most pain, Leo, is unbelievably gentle and stoic even when in severe pain -- as he was when he damaged a disk and also on and off with his SM, as well as twice with a ruptured anal gland. My vets have always commented on how he is willing to let people touch him even when it is clear this causes significant pain (but is required for an exam). The vets I had to take him to in the UK for an emergency said the same -- could not believe he allowed them to handle him when they said most dogs would probably snap at someone unfamiliar.
There's also the argument that sensitive dogs may be so because of some general underlying pain. That's certainly the feeling of neurologists on that common vet comment that cavaliers are 'cry babies' when they get injections... in the neck. Given the rate of SM/CM the neurologists feel it may be pretty painful to many cavaliers to have a needle stuck into the area where syrinxes are most likely to form and where the brain may be herniating through into the neck area of the spine.