I have a plain RC-4 and serrated RC-3. I have to say that I came with a real bias against serrations. Don't get me wrong, I like them, but I think that optimally they should cover the whole blade.
In testing out the RC-3 with serrations though, I cannot find any downside to the presence of these things. The RC-serrations behave differently than other serrations do, such as spyderco's. They don't seem to catch like more aggressive serrations do and are really easy to tune up. In Jeff's words - just sharpen them like you would a plain edge knife. For these bigger 'teeth' this works great.
This weekend I tried shaving wood with both the serrated part and plain part. I was able to shave with both parts of the edge equally, whereas this isn't usually the case in more aggressive serrations. In fact, the shaving was better on the serrated part - but I suspect that is because of the greater power in my stroke being closer to the handle.
In doing the things that the serrations are designed for, like cutting rope and seatbelts, the serrations work very good. I don't think the RC's are quite as efficient as something like a fully serrated spyderco model, but the teeth do bite hard into rope. I was going through 1/2" anchor line with relatively little effort on this knife. A plain edge can be just as good, but it has to be razor sharp at the time of the cut for ropes.
So all in all - for the RC-3 I'd recommend the serrated version. I use my RC-3 for a greater diversity of applications since it is an EDC knife and the serrations come into play more often in these varied cutting applications. For the RC-4, my intended use is still primarily wood/bushcraft type applications so plain edge is still my preferred style in this sized knife.
If I had to replace my RC-3, I would probably go with the partially serrated version. I have to stress that I don't think I would have told you the same thing before I had the opportunity to try out the serrated version though. This product really did change my mind on the subject.