While doing a stress-test run yesterday to test out some homebrew Force stuff (chief amongst them a blaster deflection/reflect talent), I noted something odd about the Antiquated Battle Droid as well as a lot of the other sample Droids provided in the Advesaries chapter.
In short, every Droid listed there has the equivalent of Padded Armor built into them.
Now for a droid that's designed to be both sturdy and combat-capable, such as the Assassin Droid or the Security Droid, this make sense. They're meant to be fairly resilient when it comes to resisting enemy fire, so having a high degree of built-in armor makes perfect sense.
However, it makes no sense for an Astromech, a Medical Droid, or a Protocol Droid to be similarly armored; after all, their main functions have little to do with combat.
And as for the Antiquated Battle Droid (aka B1 Battle Droid), those are pretty much in-setting described as being rather flimsy, as their main virtues were how cheap and easy they were to mass produce in the large numbers that the Trade Federation and Techno Union fielded, both before and during the Clone Wars. In the Prequel films and the Clone Wars series, we see B1 Battle Droids getting dropped by pretty much anything that hits them, including the standard blaster pistols that Amidala and her Handmaidens were using during the Battle of Theed. The book stats for these droids would require at least 10 damage to drop them (4 to get past their listed Soak Value, 5 for their Wound Threshold, and the final point of damage to blow past that Wound Threshold), and unless these ladies were extremely well trained in combat (3 or more Proficiency dice), I don't seem them being able to constalty roll that many successes (they'd need at least 4) or that many Advantage to constantly score a Critical Injury. Clone Troopers get a bit of a pass, since they're using Blaster Rifles or Blaster Carbines in most instances, so they'd only need a single success on their attack rolls (easy enough for them) to drop a clanker with each shot fired.
I'm thinking that with the exception of the Assassin Droid and Security Droids, all the other droids should have their Soak Values dropped, with non-combat droids having it reduced by 2 (in other words, just using straight Brawn) and the Antiquated Droids having it dropped by 1 (using Brawn plus one, since they are 4th Degree droids).