The AER 14 does not require meta-gaming. I found it my first go through because I search every where. I'm a bit OC about it. I have to completely search a place. If you consider that meta-gaming oh well. I average 200 hours a character - first character will average 300. Some of my later don't take as much time because there are places I have no desire to see again or it doesn't fit the character to go there.
I do agree with you about the La Longue. Even if my character was a legion goon I'd leave that guy alone. He has proven himself and earned the right to live - well I wouldn't murder him for the gun. Kill him in battle, so be it.
OT- I prefer the AER 14 with normal ammo. I'll keep a few max charge for really tough things like Deathclaws. Fixing it is no problem as In everygame I find/buy the makings for 120+ weapon repair kits. Other guns out there with better stats than the La Longue to warrant getting it.