I think I'm doing a 15% SF too - I can't remember off the top of my head and I'm at work so I can't look. The article only had 6.5% SF. I ran it through a calc (ran out of work to do already this morning) and its 30% CO, 60% OO, 5% each Shea Butter and Castor. With that much OO, it's going to need a longer cure to begin with. I don't think it's going to be a good bar of soap as early as she says it is.
I thought about doing a longer cure with my bars, but I'm not sure I need it. All soap will get better with a longer cure, true, but the slight increase in CO wasn't enough for me to consider a longer cure over 8 weeks. My dry skin was really happy with it at 4 weeks even. If future recipes increase the amount of CO, I will increase cure time - I think the high CO in a traditional salt bar is usually what my skin doesn't like and those take a long cure for me to tolerate using them (18+ months). It will be interesting playing with my soleseife recipe in future months, and seeing how the cure changes with more CO. Although there is part of me saying "Sherry, it ain't broke, don't fix it!"