I'm a little behind the schedule I had hoped for last post, but that's it. I'm calling Act III done. The last playthrough was largely successful, though it generated several small issues (misspellings and the like) which are now all taken care of.
So last night I started through the entire campaign and have already come across a couple show-stoppers that I need to clean up. I haven't really looked at Act I in a great many months (years even), and it's obvious that one of the patches did some damage. Luckily, Act I is rather small in comparison to the others, and most of it seems to work just fine. I think I'll only need a little bit to get all back in order and then proceed onwards. Acts II and III have been largely completed and tested since the last patch came out, so I don't expect anything similar to crop up later.
The other source of possible issues is that I'm doing my campaign-level testing with a male PC and the majority of my testing to date has been done with a female PC. The only difference is that the companions are different, have different dialogs, and have a few different interjections. I don't expect much to go wrong because of this, but it's likely to be a bit rougher than a female PC would be at this stage. Fingers crossed!