Iver-Johnson - That's a name I haven't heard in a long time. I don't know much about them, but they are reputable. I can't speak at all about the safety mechanisms, but I'd be pretty hard-pressed to find something unsafe about my small Colt revolver.
Dissapears completly in smartcarry, or very convenient in a jacket pocket in cool weather. If I'm expecting trouble, SP101 in .357 mag, Hydras. It doesn't hide quite as well because I'm small, and it hurts to shoot with a magnum load, so you won't shoot casually, and if it hurts me to shoot it, I'm comfy that it will hurt the one shot a lot more.
.357 is a very good, potent cartridge. I have a Python in the safe, but I don't intend to carry it. Its a wonderful gun to shoot, with a very clean, buttery-smooth trigger action, but I'd rather not put holster wear on such a fine weapon. I have other choices.
Right now, the little Colt Det. Spec. .38 is sporting +P hollowpoints for that little extra "oomph" when I fire it.