In Necromunda if you had someone captured you could do 1 rescue scenario to try and get them back without paying the ransom. If you are playing with these rules then the blowpipe becomes *much* more useful because you can fire it without alerting sentries, thus making it more likely that you will succeed.
We use such a scenario in my circle and it helps ransom negotiatons not be too brutal because the person making the ransom knows if they get too greedy then the person with the captured hero will likely do a rescue to try to get them back. On the other hand, the person wanting their hero back is likely to take the initial offer, because they know that if they try the rescue and fail then the person with the prisoner is now entitled to really put the screws on for what they want. It adds an interesting dynamic and means that the advantage for players that have access to the bounty hunter isn't so great.