No I haven't done much in pots, I am not sure if they would compete with each other but I kind of doubt it would be a problem. You could always prune the basil often to limit it's size.
If you are worried I think you could get similar benefits but putting a few separate pots planted with basil near the tomatoes.
I might try both and see what works, thanks! I'd like to grow enough basil this year to make homemade pesto:-)
I love pesto! It is an under appreciated condiment/food.