You shouldnt shoor lead, unjacketed rounds in your factory glock barrel, this is because the polygonol rifling is more suseptible to leading than barrels with standard rifling (storm lake, bar-sto, lone wolf).
The reason that reloading for a g23 may be more risky is because of the previously stated fact and also that the chamber support for older glocks in 40 cal wasn't quite what it is today, which is still a little less supported than other competitors. Although , say if you have a 3rd gen 23, I wouldn't sweat it. This loose chmaber also sometimes results in spent casings being a little swollen at the end near the primer, this makes reusing brass a bit more complicated.
Most issues that relate to safety of you and the gun are caused by stupidity. If you want to shoot lead out of your 23, get an aftermarket barrel with standard rifling, if you pay attention when adding powder.
In short reloading for a g23 requires only a bit more caution than anyother gun, in that the rifling is differnt, this wont effect you if you load FMJS or JHPs. Also if your brass gets a potbelly, or out of shape, you have a little more work to do.