Good question, Dave...
It is my opinion that it is OK to yo-yo with this WOE and here's why:
It would be far better for you to remain LC and never deviate, but as long as you return to LCing and resist the urge to abandon all efforts to follow a healthy eating program, you'll be ahead of the game. Yo-yo or not.
In my own experience with LCing and falling off the wagon for brief periods, I have contiunued to lose weight when I return to LCing. However, when I have done so, I always start from step one. I do the two week Induction period by the book. I don't try to delude myself into thinking I can just resume where I left off. This program works by getting everything lined up in the right order, and that means 2 weeks of Induction level eating when you return to LCing.
I also happen to believe in the power of positive thinking and visualization. I think if you convince yourself that you won't be successful at LCing becasue you have yo-yo'd several times, then you're sure to fail. On the other hand, I strongly believe that if I strongly believe and make a commitment to myself, I can not be stopped--no matter what.
As for it being "harder" to get back to LCing in general, I haven not found that to be true. For me, when I have returned to LCing, the foods taste so good! Far better than the feelings I get for sugary foods.
Thanks for posting this interesting question!
Donald