I think I confirmed that lords are NOT respawning after defeat in 156_B11, at least if you are not a vassal of any faction.
Testing method:
1) Turn warband cheats on (not cheat mode; key command cheats)
2) Make note of a couple defeated lords in the message log, in my case a couple veiger lords (tansugai & ch-something)
3) Wait a few days in game, ctrl+t for a few frames to reveal map. This should make all character location reports current, if they're
on the map
4) Check notes, characters for those lords' locations. In my case, both defeated lords had old locations reported (5 and 9 days old)
I also asked khergit lords for the locations of the defeated lords from step 2, they all said "I don't know where ... is". Also, many lords form many factions didn't have locations reported at all. I suspect these are lords whom I never saw before they were defeated and never respawned, though I guess the test I listed doesn't confirm this theory. I was not a vassal of any faction when I did this test, I have not checked if lords respawn if you are a vassal.
Just to check though, the red text displaying version number in on the main menu in B11 should still say B10 right? I've tried installing the B11 patch from both moddb and nexus, both leave the main menu version number as B10.