I didn't read all the replies, but here's my two cents:
I bought an x-pen for Catherine to help with the potty training - no dice, she just climbed out of it. We tried for a long time with the stupid pen and she kept climbing out. It was too dangerous to keep her in it because she'd try and try until she got out. Fortunately she never hurt herself...
I tried my best to train her other ways, like walking on a schedule, etc, but it didn't work, she would still sneak around and pee - mostly in my daughter's room.
Finally bought a crate (I got the medium size so she can have her toys and food in there with her bed). It has works like a charm! No accidents since I got it. She now knows the only place to go potty is outside the house.
Next we are starting with the hanging door bells and going to try to train her to use those.
Just my experience with the pens.
