have no first had experience whilst exceeding Vmo, however...I know some of the Lockheed test pilots that did, and they report no particular problems exceeding Vmo by 30 knots and Mmo...to M.98 (Mmo M.90)
Though this may be relevant, I think one needs to be a little wary of the 'I know somebody that got away with it' argument. This is a little prone to what statisticians refer to as 'sampling bias': you aren't likely to have a conversation with somebody who tried it, and killed themself in the process...