The right package can be carried very easily in SOB. I've done this with guns and knives and it's certainly a viable carry option.
The disadvantage is that in the most common carry config (horizontal), you limit yourself to use with one hand only. If that hand is disabled or "busy", your knife is no use to you because you can't get to it.
Lately I've preferred an IWB front carry at 10:00 or 2:00. This lets me use either hand to access my knife. Since I always wear my shirts out and fairly loose rather than in and fitted, my waistband (and whatever is in it) is always covered anyway.
"If there are no dogs in Heaven, then when I die I want to go where they went." - Will Rogers 1879-1935