I meant to post this a couple of days ago.
Bot navigation is a not very well covered topic. Cardigan wrote an article on it, I expanded on it.
TBH Pat, if you are just bot clipping stairs there is no need to run -fixaas. Normally you would do that to simplify something extremely complex. You may have been joking, I'm not sure
More often than not really stupid bot behaviour is caused by tiny clusters. Stuff like running up to Red Armour, then turning away and running in the opposite direction.
An ideal map for bots is a map that is a single cluster. In such a map bots can see everything, all the time. The problem in large maps though can be 'bot stutter', were performance takes a hit, in much the same way as a map with poor vis control.
The best answer is to use cluster portals to control cluster creation, but this takes time to master, and also doesn't prevent the creation of tiny clusters that screw up navigation.
I used to spend a lot of time finding these little blighters and getting rid of them. There were a number of approaches I used. A targeted entity that exists in 2 clusters will merge clusters, as will a series of complex cluster portals. The latter is a bit of a hack, but works well.
