The E-collar that I got for Kali came with rubber tips also. It's supposed to help save the fur but it also dumbs down the shock. So I guess it's a individual thing. Most people use it without the rubber tips. I started with them on but they eventually fell off and I didn't even notice.
For me, on a little dog like Kali, I'm not using it like you would on a doberman.... Tight and high around the neck. For her, it's just floating loosely on her neck because all I use is the sound and sometimes vibration. And she can feel the vibration even though its not tight to her neck. She's excellent with the sound alone.