I'm with mooman, I really don't like any fake things in my tanks.
I have used flower pots though. What I did was cut them in half and bury them under gravel. You could cut that large pot in half. Put one half on each side bury them with sand and put some of the rocks on top and in front. That way you'll still have the cave, but it will blend in a lot better. Between the two I like #1 the most.