Rosie I found as I gained more experience I could tell if they needed watering by pot weight. I'm using clear slotted plastic pots for everything but I have found that different brands and styles of clear slotted pots dry out way faster than others. I agree with Bill, the size/type of medium isn't so important as long as you adjust your watering accordingly.
I've heard the complex Paphs are trickier to grow. They seem to be touchier to too much or too little water. I only have one and it seems to be growing nicely in large fir bark. We'll see if I can get it to rebloom!
