DoubleTapDrew:
On the contrary. The shoulder holster is no easier to block if wearer has a little training in body mechanics and weapons retention.
As for IWB, it works for some, not for others. My wife and I are both very short-waisted. It just doesn't work for us. Shoulder and pocket holster work for me. Most of the time I wear a vest, Scott eVest or 5.11 Tactical's vest. The 5.11 is designed for concealed carry and has an innovative "Belt Backup" system of modular velcro pouches including a holster. the eVest is not designed for CCW, but it has adopted the velcro carrying system in part. It also has enough pockets to fit several pistols, all your reloads, firstaid kit, twenty different electronic devices and a Dillon Progressive Reloading Press.
The J. R. Noble Leather Company in Vancouver, Washington makes an excellent vertical shoulder holster. They would prefer that you come in to get it custom fitted to you and your weapon and then come back later for final adjustments. I've been very happy with it. You have to trust to whatever safety you have and the covered trigger.
A lot of people scorn small-of-back carry saying that you can break your back if you fall. In defense of S.O.B., many of them are also range owners who forbid shoulder holster carry. Both cause you sweep your neighbors when you draw. As an experiment I took a Blue Gun replica of a Glock 17 and several holsters. I took ukemi from a variety of positions with each of them. The worst bruising was from a FOBUS paddle holster and my WIB rig. Falling on my back was unpleasant but not as bad. The most painful was the sharp blow to my bladder from falling forward with a fanny pack. YMMV. Use only as directed. Most people haven't had as much experience falling down as I.