Yea I do agree with that, frogs can def. get in the cracks. I always put sphagnum moss around the edges around the walls to prevent that. You have to take extra precautions. Yes, it is about preference, I just hate that its hard to get the screen over hose balls.Actually you can buy a 50lb bag of hydroton at most hydroponics stores for $25 -$30, and that will last you for many a tank. Another advantage of clay is that if you do not build your false bottoms extremely well (no gaps), frogs can and will find their way under that false bottom.
There are a bunch of threads on this, and it is in the end, personal preference.