The CS SK5 is definitely plenty good. The main advantage besides rust resistance is that the San Mai version has is that it's more resistant to flex, and is a bit tougher. Basically, the outer steel is a stainless, I think 420J2, but don't quote me on that, and the center is a high carbon steel. They're tempered differently, so the edge retains the cutting ability and edge retention, while the outer metal is softer. General rule is that you want the edge to be nice and hard for edge retention, but the harder the metal, the more brittle it is. So, they sandwich it in softer metal, which is more flexible, to preserve toughness AND edge retention.
I'm not sure that you'd need that, but honestly, if you're going to be spending the money on a San Mai, I'd forgo Cold Steel entirely and get a Himalayan Imports khuk. Heck, you can pick up deal of the day khuks or blems for not much more than the price of the SK5 version, and honestly, once I went HI, I never went back. The CS kraton is grippy and that's usually nice in a knife, especially because it doesn't have the traditional design, but it tears the heck out of my citified hands if I try to do some heavy chopping without wearing gloves. Even the smoother Ka-bar kukri machete has had complaints about that issue. The HI handles are wood, and the bottom is flared out in the traditional way, so it can't fly out of your hand, and if you're using it correctly with the loose grip, it's just a lot more comfortable to chop with.
It's also worth making sure you know how to swing it--it's a momentum tool, so you want to grip loosely, mainly using the thumb and forefinger, and then letting the blade swing down into the wood/target, whatever you're chopping. Definitely consider reading the safety thread in the HI subforums, as a khukuri handles differently than most blades, and can easily take a limb off if you mess up and hit yourself.
As for not being able to use it as a knife, I don't know about that. It's the all-around tool for the Nepalese. They can do anything and everything with it. If you get an HI one, you also get a small knife and sharpener, called a karda and a chakma, so you can do precision small cutting tasks, and smooth out rolled edges in the field.