I now consider SUSS (Steve's UtilityAi SubSystem for #unreal) to be a decent Alpha (I've even tagged it!). It's behaving quite nicely in our game and while I'm sure there's more to improve, I'm pretty confident that it's usable for those happy to take the plunge.
I only started it about 2 months ago and it's my first foray into Utility AI, so you know, buyer* beware 😛