hiya! I've had my own trial run of sjk in for almost a month now, and i wasn't initially impressed at all however after a few washes and treating them kindly they are pretty good i must say, only a few strands that are tuggy around the "colour join" as i have dip dye 6-22 in just now.
I wouldn't say particularly better than hairplanet, definitely budget hair but I do like the fact that the girls are very easy to contact, as seem to genuinely do what they can to help you out.
I fitted a set of the 1.1g strands the other day on a girl with particularly thick (and short!!) hair, and used 175 bonds, it looked lovely top to bottom and sat nicely once it was all cut and blended so for someone like her it was ideal, but I'm not sure about using it yet on my "regular" haired clients xxx