Here is my meaningless drivel. . . .
First, a M19 is an awesome gun and I would hate to see you give that up for CCW. Have you tried a good IWB like a Milt Sparks? I have their Heritage #1 and it makes a 5" 1911, pure joy, except the weight.
On to Glock vs 1911. You asked for safest. . .The 1911 would be safest. A cocked and locked 1911 has a manual thumb safety which snaps on and off rather "smartly." It also has a grip safety. For this discussion, we'll call those active safeties since they require some effort outside of pulling the trigger to deactivate them. With proper training, they can both be activated when holstering your weapon. Glock does not have an active safety and some Glock users have had trouble reholstering. The 1911's thumb safety could also be engaged when holding someone at gunpoint.
On the other hand, all Glocks are "drop safe" while only some 1911's are.
Simplicity of maintenance and use. A 1911 requires regular spring maintenance for mag springs and recoil springs. Glock owners typically never change either.
Glocks are almost always 100% reliable OOTB. 1911's while good, are sometimes not 100%. Shorter ones are worse. Some even argue that the short ones cannot be 100%. Mine, with maintained springs are 100%.
Last, a shameless plug. Maybe a SA XDM would be a good compromise??