Archer thralls in a base should shoot at trespassers at a distance. Sure, give PC’s slightly greater range but Thralls should engage unalighed PC’s at a pretty long range if they are archers. They should aggro in the same way as NPC’s - If a player that isn’t in your clan comes close within about 20 squares they should start firing at the enemy PC or if they are melee they should charge the trespasser.
The way thralls work now there is no way to defend tier 1 or 2 bases. I think in tier 3 you get anti-climbing spikes but for tier 1 or 2 bases you are pretty much helpless.
What I see happening in the future of this game is in a few months there will be no way to progress in this game on a PvP server unless you join a clan that has a tier 3 base already established. There is nothing to prevent anyone from climbing your tier 2 walls. At least if you had some archers that shoot on sight they could shoot climbers, or attack a climber as soon as he got up the wall when their endurance is low. But now an invader can climb the wall, take a breather, have a cup of tea, then take out the thralls one by one with nice long meal breaks in between to keep their health up.