This is the answer. According to Rigging For Rescue of Ouray, CO, the ratio of prusik cord diameter to host rope diameter is 2/3 to 3/4.
Mike must have changed the numbers when he bought the company from Kirk. Gotta do something to be different - Typical
Use a rule of thumb for prusik cord: 60% - 80% of the host rope. So for 8mm rope, 5 works great & 6 will work but you may want an extra wrap with the 6mm.
Nice TR & Pics. One question though: How long did it take your party to summit?
I am planning on an attempt this weekend weather permitting.
Thanks
Coop