When performing a left leaing decrease on a piece that is knit densely, like socks, I always do an SSK but I slip as if to knit on the first slip and as if to purl on the second rather then both as if to knit, I think the stitch lays more flatly that way. However, in knittling lace I find I can get away with the faster k2tbl (knit two through back loop) in most cases and not really be able to tell the difference. I learned this when kniting the Chevron Scarf from Arctic Lace, in this book all left leaning decreases are K2tbl and they look fine, so I started doing that for all the lace projects that I knit, until now. I'm kintting with a hemp/cotton blend yarn and the SSK looks just the tinnest bit tidier then the k2tbl (yes, I am guilty of doing both methods in the same project - it's the only way I can compare how they differ.) I guess it's the smoother texture of the yarn and maybe lack of elasticity. I'm curious to see if anyone else experiments with this.