Those are probably users and/or investors you're better off not having. Conversely, answering "we're not sure, but here are some parameters of the situation / dimensions" suggests you're at least cognizant of the area.
There's also the case of implausible ignorance: the "I don't recall" defense popular in politics and business PR-speak. This tends to decrease credibility.
There's also the case of implausible ignorance: the "I don't recall" defense popular in politics and business PR-speak. This tends to decrease credibility.