I used to play Kata jungle a lot.
I must admit Kata has very slow start as jungler, because low sustain. It's very easy to outplay and counterjungle her before her 6.
After few levels and some itemization her jungle clear is very fast, and ganking potential is high. Runic echo is like the Luden's echo on stats, so itemization is not much different from Kata-mid. Also that item give here two wards, so its more easy to ward-jump and vision control. Runic echo is a bit worse than Ludens, but much better than Runic glave, that was last year.

I played Kata-jungle even against gold/plat players quite successful.
My opinion playing off-meta is not trolling. But banning other players main champs is definitely trolling. Off-meta is always unexpecting to enemy (you can play teemo-jungle actually). I've seen diamond played Ashe jungle with 12/3/14 score. So, its a game. I dont strict others how to play their game. Kata-jungle is fun if you main her. It's like saying "Teemo is not meta - dont play him".
P.S. As said Sphyxx in this topic. You should start with ad runes, first W and first item must be
, it heals you more than
. Clear order must be: Kragg, Scuttle Crab, Red buff, Wolfs, Other crab, back to base.