If I may offer a shameless plug, I think that my treatment of the Byrne variation (and related lines) in my book Opening Repertoire: The Modern Samisch is very good.  I wouldn't recommend the Byrne Variation to a player of the Black pieces.

It got covered back in the January KID update here - seemingly far from fixed, and even slightly mysterious,  status wise.

LC0 seems to agree - it thinks lots of ways white can keep a normative edge, but nothing more than that and there's no single coherent plan it follows for white.

Definitely also check the recent a6, Nbd7 move order - black can avoid having to play c6 entirely vs several white move orders, and has been winning some awfully nice games that way.

I noted this to be the most troubling variation for white in the games I played as black, even when I was the weaker player (way back in the day) and ended my fear of the saemisch. How is its reputation these days? It doesn't seem to be employed all that much in famous games. It's mostly main line or panno..


Byrne Variation: 6...c6 and 6...a6 [edit]
Robert Byrne developed a flexible approach where Black plays ...c6 and ...a6 in order to prepare the push ...b5.[18] Black's direct counterstrike in the centre is postponed so that the queenside advance can proceed quickly.

White can decide to halt Black's ...b5 break by playing 7.a4 at the cost of weakening the dark squares on the queenside. After 7...a5, Black has gained control over the b4-square, and will usually win the c5-square as well.