MN:PE 2 - full pancake a prerequisite?

I believe Ravn once posted at length about why he had moved on despite not having achieved the same degree of compression as the athlete in the video. I believe he's working on the stall bar progressions now. I've been considering following his approach for a few weeks now. It would be interesting to hear from him and see if his compression in Mn/PE2 has improved after working on the stall bar for the past year or so. 

You are correct about the spinal mobility being about the same as MN/PE1 Kibbokit. The hip flexion really isn't much if any more than PE1 either though (maybe very slightly more but not much). The big different between the two is that the legs must remain locked straight for PE2, which requires much more active hamstring flexibility compared to PE1. The passive ROM (at least the hip flexion/hamstring part anyhow) should have already been built if you've mastered MN/PE1>iM and MN/PE2>iM should be continuing to improve your flexibility in this area.

I was only mentioning the spinal flexion component because it changes the biomechanics from an active pancake, which would seek to have the pelvis anteriorly tilted/lumbar spine arched, to what is demoed in the F course which requires a posteriorly tilted pelvis/rounded lower back.