Finally I managed to spend some time playing Fixt 4.1, I've just finished it.
I've installed it onto clean english version installed, with weapon drop mod installed and the "slowest" possible version of mutants' invasion. I encountered some bugs, glitches, whatever.
1) Same problem as Oppen describes two posts above.
2) Prisoner at Khans - even after I've killed all raiders he didn't realized it and just stay in his opened prison cell, and there was no specific dialogue option to tell him he's free.
3) Super Mutants in Watershed - after I killed them all game didn't realized that (both Seth [no proper dialogue option] and Pipboy [quest weren't crossed out]).
4) Ghoul Manager at Hotel in Necropolis still talked only errors.
5) Adytum - something is wrong with Blades/Regulators conflict and their final fight in Adytum. I've tried many times to accomplished quest and finally I managed to, but I think still something went wrong. What I've done: talked to Zimmerman - talked to Razor, get holodisk - killed deathclaws for Gun Runners, told them "friends needs weapons blah blah" - talked to Razor - and now:
a) see Zimmerman before attack - first attempt - Zimmerman killed, regulators started slaughter, Blades appeared (only one time they appeared, unfortunately Miles got killed so I have to reload); second attempt - Zimmerman killed, slaughter, no Blades. Soon I/Miles/Smitty got killed - reload. And so on. If I try to escape from slaughter and tell Blades what happened, there was no Razor - she disappeared.
so I managed to complete the quest b) without bringing holodisk from Razor to Zimmerman, only if I decided to take part in Blades' attack just after they got their stuff from Gun Runners.
6) In various number of places, while fight, game told me that I can't shoot because line is blocked blah blah even in such weird situations like my character standing eye to eye with an enemy.
Anyway, great work Sduibek, great as usual.