I've had a David Paradise, a Proteus, and an InnerPulse, which is the machine I use now. I liked the Paradise but it quite working after about 6 months and was unreliable up to that point. The Proteus was a decent machine. The lights were too bright for my tastes, and the presets lacked variety. I did not want to do the work to learn how to program it.
I now have an InnerPulse and am very happy. It has a great variety of sessions and the leds are smaller and not as bright as those on the Proteus.
I bought both my Proteus and my InnerPulse from Dynamind.
http://www.dynamind.com/ls.htm
They were the cheapest source I could find at the time I bought my machines and they did not charge for shipping. They shipped quickly.
I use the InnerPulse exclusively with hypnosis tapes. I have never used it for meditation or entertainment. It is a great tool and deepens hypnosis for me.
I have used it with Paraliminals and with a number of other hypnosis tapes.
I found it to be a worthwhile purchase. I am not sure a light/sound machine is for everyone, however.