I have used IPL with Radio frequency for over 2 years now and have seen great results. I find it helps so much with skin types 4 and 5 as the advantage is you do not have your IPL energy as high as traditional IPL to get the same result as the radio frequency brings extra heat to the area so to speak. So it is much safer on the skins surface.
It also helps more on the lighter brown hairs also making the treatment more effective.
A lady came to have a demo with the machine a month or so ago for hair removal on her underarm and she had a treatment also with another company on her other underarm and said that she couldn't feel the treatment as much. She thought it wasn't going to work as well because it didn't feel as strong but then was so happy to see that the result was better than the other company!
I don't think it is pain free personally you still do feel a flick but just not as strong as other IPL machines that don't have the option of radio frequency in it.