One issue I've been having when attacking with the shin guard from the sitting/Cobra guard is when guys cut the knee sharply in a Royler style pass. I remember the last time I rolled with Cindy no gi, she avoided my shin guard with a very sharp, almost sideways, knee cross.
The trick is to get more control of the knee. Enter the shin guard, but then move in close to really hug the knee. Your shin will be fully contracted against your thigh, but remember that the hook in this instance isn't so much a traditional butterfly hook (where you'd want your shin/lower leg further away from your thigh) and more a block to keep the guy's lower leg in place as you roll back into single X or the full X-guard.
The Jeff Glover Homer v.s. Standing sweep might be there, though you'd want to get rid of the hook and lock the lower leg instead.
