I'm certainly no Becker expert, as the only Becker I have is a regular BK2. In fact, I didn't even know there was a serrated BK2 until your post. However, my first reaction is, "no, probably not worth it". I'm sure it's still a well-made knife, like any Becker. However, what is the purpose of it? If you are needing a knife because you are working with a lot of rope or fibrous material, then the extra weight and thickness behind a BK2 really aren't going to benefit you for the push/pull cutting that you would be doing.
Alternately, if you're still doing some of the chopping, hacking, batoning at which the BK2 excels (for a knife its size), then the serrations might actually make the BK less effective at that (or at least the edge more fragile as you're doing that). I'm not positive on that; maybe someone could comment on the physics involved in that case.
Given the steel of the BK2, it's fairly easy to maintain a plain-edge BK2 in the field. However, sharpening serrations is much more time consuming/challenging than a normal plain edge, and sharpening serrations is not something I would want to worry about on a bug-out, just-keeps-going knife like the BK2. So in my amateur opinion, putting serrations on a BK2 just doesn't seem to mesh with the other design aspects of the knife.