Ok a little more success now
I tried what you wrote, and I successfully get instagibCTF on the server, but the map is still freakin' Arsenal.. So it's iCTF on DM-Arsenal. My provider have put all the maps in this folder: /ut3/UTGame/CookedPC/Private/Maps/
Maybe I have to specify where the game needs to be looking for the maps? Although that doesn't make sense, since DM-Arsenal is in that directory as well. There are only a few maps in the default map directory (/ut3/UTGame/CookedPC/Maps/), neither of which are CTF-Reflection or DM-Arsenal.
What the fudge am I doing wrong?
Also, my UTstartup.ini now looks like this:
CTF-Reflection?Game=UTGameContent.UTCTFGame_Content?Ga meMode=1?Mutator=UTGame.UTMutator_instagib?GamePas sword=?AdminPassword=blabasd