Galas peak I'd still love to see those ice skaarj. Next time I've got access to the editor I'll see if I can effectively swap some in. The only thing I'd be changing is the difficulty pawns appear on, and make it so that if any skaarj see any mercs they'll fight each other (I believe you just have to set their team-tag...?). The only way a merc/ice skaarj fight would happen is if you retreated and caused a skaarj to follow you into a room full of mercs. Otherwise everything would be as you left it.
I think it should be either all Skaarj, all Mercs, or staged fights between the two - like I did with the pirates vs. mercs. Otherwise, It looks like they are just roaming the peak oblivious of each others presence. If the Skaarj had control of the base, the Mercs would be raiding it rather than just standing around or patrolling. Some well staged fights might spruce things up.
I think the only mutator I was using was the one to get old weapon sounds back. (That's the only one I use for SP games)
Are you using Waffnuffly's V1 sounds mod? If so, then that is definitely the culprit. The mod reverts some things back to Unreal version 1 behavior, causing strange side effects. It causes some monsters to not pick up their weapons, as well as removes permanent decals in Old Skool (and probably RTNPUE). In order to get the old weapon sounds back in my own install without other side effects, I simply made a copy of botpack.u, modified it to have the old Unreal sounds, and created a batch file to swap them in and out accordingly. So if I'm playing UT multiplayer, I click on "V1 sounds uninstall.bat", and it replaces the V1 sounds botpack.u with the original.
Anyway, thanks for keeping me in the loop if you update anything. Let me know what you come up with if you do.