First and foremost I trust myself to be able to determine what is a threat to me and mine. I also know in the examples given, taking a 50yd shot for the purpose of self defense is unlikely. I could happen in some far reaching situation. I spend my training time on the things I deem more useful as everybody should, for you and others thats long shots with pistols and that's cool. I too have tried long shoots for fun, but it's not what I train.
When it comes to defense a getaway is as effective as an attack. At 50yds I think a getaway would be favorable to an attack or to the point defense with a gun. Any prosecutor would question why one did not run, escape, hid, drive off etc. What is the defense in court, "I was sure my full sized gun could make the shoot cause I practice gun fu" or "any one firing a gun in my vacinity is a threat so I took them down". You do know that compact guns can make a 50yd shoot, right.
I just have questioned the need to have to do it, others have pointed out and rightly so if it would be legal, in my state the cases purposed are not legal and for me not prudent or safe.
RR's rule for a gunfight, get home safe, by any means, and that may mean avoid the fight altogether. What has been described so far is street justice, not defense.