If you gonna play shaco, you pretty much have to be fully dedicated to it if you want to be good at it. So be prepare to play almost every game as Shaco. If you are prepared for it and like it, its ok to do it, objectively speaking, there are players in diamond that pretty much only play Shaco.
For lower elo, I don't think he is a good choice to use to climb out of lower elo. Let's be honest, in low elo when did you see a team or yourself understand fully objective to go? when to group up? when to only wave clear so your teamate can split push? when to avoid teamfight? pretty much never. I am also in low elo, so I can see that my teamate don't understand these concept just like I also don't really understand them. Basically what I want to say is, in low elo, most of the players do not understand how to make macro decisions correctly.
And shaco requires the his team to act corretly in a very different way compare to other champion. This in turns means it makes macro decisions even more complex and harder to understand. Combine these 2 facts alone, it already drastically make your game much harder to win.
Don't use KDA to justify playing a champion in rank, if you want to climb, look at how is your win % with the champion. (If you want to justify it being fun cause you like killing other champions alot, then thats different.)
P.S. This is just a side note. I think you mean a high KDA ratio not positive KDA. Since its always positive.
KDA Ratio = (K+A) / Max(1,D)
So its almost always a positive number. The lowest it can go is 0, which is (0+0)/Deaths.
Edit: The correct fomula is KDA Ratio = (K+A) / Max(1,D). Editted that in.