Vacuum mechanical gyros were used until about the 1960's when lasers (RLGs) were introduced. In the 90's, some RLGs were replaced by HRGs where space is at a premium for Q around 1e7-8. Very large RLGs are still used to detect very slow rotation and can have Q factors on the order of 1e13.
Yes, also, while I have only worked on military boats and never on subs, I can straight away tell you that anyone who would know anything remotely interesting or close to the cutting edge regarding inertial navigation system for subs wouldn't be able to talk about it.
It's one of these subjects where you will never get anything better that vague press releases designed to justify research budgets.
