I'm not sure if that would be considered a security breach perse, even if they knew they were using keepass that doesn't automatically give them access to their offline encrypted data vaults. Other than a dubious google ad for keepass that claims its trusted by NASA, there's a Government Furnished Computer Software report [here], last updated around, 2015 I think? It indicates a series of software packages used by a few NASA agencies, specifically [Confidential Close Call Reporting System] and the [Aviation Safety Reporting System]. Granted though this doesn't include NASA or NASA laptops themselves, so i'll correct that.

KeePass is great. I'm using KeeAnywhere right now, enabling me to access my password database stored in a Dropbox account from almost anywhere, and the KeePass Touch app works great on iOS, allowing me to edit and access my passwords from the go and use them on my iPhone. It also allows to use the Apple Keyring feature, enabling Safari to autotype your username and password data on relevant pages.
Best Regards.
Hijacker

Yep, count me in as another happy keePass user. I've been using it for about 3 years now, and I agree that the KeePass Touch app is great. I don't want to keep my vault on Dropbox, encryption or no encryption, and this is why I personally don't like cloud-based password managers.

There's also the fact that I use it to store things other than logins, such as keys for games and software that I've purchased. The beauty of having a non cloud-based solution in these circumstances is that I can install things even if I don't have an internet connection, unless the software in question has to phone home, of course. Even so, it's a good use for a password manager that I don't think a lot of people take into account. I got tired of misplacing emails, or text files with keys in them, and one day I had an aha moment and just added all of them into my KeePass vault.

As for taking your vault with you, honestly I don't see that as being that much of an issue. Flash drives are so tiny these days that they're easy to lose if you're not careful, so they're certainly portable. it also pays to keep several backups of the vault file anyway, just in case you lose one. Also, if you're going to be running KeePass on multiple computers, I'd recommend putting the portable version on the flash drive along with your vault.