I don't believe the Rainbow leek comes in S30V. The S30V Leek is a new knife with G-10 scales (part K1660G10). The $55 Blur has to only have the 440A blade steel (again, unless you are getting ripped off). The S30V Blur is about $78 dollars and is also a new knife. Which ever one you get, spend the extra and go for the S30V steel. 440A can get a good edge but it won't hold up very long. S30V is great knife steel.
The knives are designed for different purposes. If you use your knife a lot around the house or at work, I would recommend the Leek. Better blade shape and handle for that type of use then the Blur. Leek can still be used for self defense also, of course. So can a pencil, for that matter.
If your main reason is for self defense and learning for use a knife in that way, then the Blur in S30V is hard to beat. With the upgrade to the better steel, Kershaw has created one of the nicest tactical knives on the market. I'm not big on liner locks but this one I even own because of the quality, the features (good grip, comfortable to use, thumb studs grooved and turned to an angle, assisted opening, legal to carry concealled in my state), and type of blade steel used.
Just think about your needs. Both are nice knives with the addition of the S30V steel. Good luck