Packing a gun in a pack does seem a bit like purse carry. It really is not on body, though the downside can be partially ameliorated via mindset and ingrained habit. Still, fall down an embankment and dislodge your pack and you are now disarmed, habit or no. Maybe I fell down too many muddy embankments, though.
Also, am I the only one for whom the safepacker screams "gun." Moreso than a fanny pack or shootme vest, which can be somewhat decoyed and are more common.