I do not use this particular device. Having looked at the picture of it though and I just have to wonder what size gouges it will accept? What are you going to use for other than gouge shaped tools?
I believe I would still prefer to use my Tormek since I believe a grinder is not the best device to sharpen wood working tools. Others have great success with their grinders, but I don't favor the idea of grinding away all that tool metal myself.
I found a site on the web that had a plan for a homemade version of the vari-grind. I built it for about $25 and 2 hours and works like a champ. It ensures repeatability in the angle of your grind.
As mentioned, looks like skews and other flat tools could not be sharpened with it.
Take a look at the Wolverine and PSI knock-off. They are very much becoming the standards for turning tool sharpening.