We actually hear of exceptional probe feats fairly often. Indeed, the earliest probes mentioned, such as Friendship 1, seem to greatly outperform not only the starships of the era, but also starships of significantly later eras.
We might argue that probes achieve great propulsive performance because they can do something crewed vessels cannot - say, maintain a more intense warp field or run on a more capable power source or other technology that will do serious harm to any humanoids nearby. Packing K'Ehleyr in one of those deathtraps might not be inconsistent with this; it would merely highlight her bravery and/or devotion to the mission... A bit like how the pilots of German rocket-powered interceptors agreed not just to operating aircraft that had high odds of blowing up on their own, but to sitting in cockpits whose poisonous rocket fuel fumes were certain
to kill them after a relatively low number of missions regardless of mission success.