I thought the same thing when I was building mine. I thought cutting that much material from the rudder and the block would be weaker then a simple hole.

I decided to use an IMP rudder control horn from Central Hobbies.

That way I just drilled a small hole in the block and hardend the block with CA.

I have over 100 flights on my first Integral with no problems so far.
The 2nd Integral is set up that way. I also opted with Integral #2 to use pushrods and a single servo for elevator control. My opinion is the plane flies better and locks in at lower speeds without the weight in the stab. The tail of the plane flies without the weight in the stab.
Pictures are avilable if anyone is interested in my setup.

Carl