Does it disrupt the flow of Primary? It's a little different, five minutes without a jump back but then primary goes a little weird after badha konasana anyway. If I slipped it into Primary earlier in the sequence it might be disruptive but by the time I get to Kukkutasana I'm pretty settled into the rhythm of the practice, it becomes a welcome change of pace, refreshing to work yourself deeper and deeper into a pose.
The other Vinyasa Krama additions I've made have tended to be the odd pose or Mudra here and there. I'm being careful not to overbalance the series. If I wanted to do an inverted Subroutine in headstands, say, then I would probably drop this one and do the inverted instead. So far it's been working out well, practice has been excellent this week.
Taking a rest day today as I think I might be going down with something. Woke up dizzy yesterday, kept veering to the right and banging into things. Standing was quite comical, it was as if I was practicing on a boat in rough seas. Managed to get through the practice but was feeling nauseous through all the forward bends. I checked and I haven't taken a rest day since 31st march, must force myself to take one a week, perhaps just some extended Pranayama and meditation later today and leave it at that.