I use a x pen when I am at work for Cooper and Oliver. I am gone for 3-4 hrs. a day and they don't potty on the floor. I do have concrete floors and they love it. It is cool in the summer and warm in the winter. My dogs are potty trained to go outside as well. After about a month of training,I say dogs in and they go right in and when I get home, no accidents and they LOVE going in it. I think it gives them a sense of security since my house is kinda big and long.
Thumbs up for the x-pen! It is a life saver for time away from home or even for traveling with my little guys.