Greets,
I am not sure that the visualator is a three panel mask. Having said that, you will hear many put them down as "orange shovels", behemoths, etc. While many do have a larger volume than other masks, many of the newer models are specifically designed to have an interior volume much more in line with standard two panel masks. I cannot speak to the visualator, but I can give you my experiences with my 4 panel mask.
I currently have the ScubaPro ClearVu2, which is a 4 panel mask, and I like it very much. It does indeed give me a wider field of view than a standard two panel mask, and the volume is between the Mares X-Vision and the Mares Demon, based on my measurements. The side panels do not distort the view, as far as I can tell. I have just purchased the newest 4 panel mask from ScubaPro, the ClearVu4, which now has more teardropped lenses, to increase the view downward. I have yet to dive with it. I tested my mask against the Mares X-Vision line and the Demon, and mine had a better fit for my face, and a wider field of view.
You could call and talk with the guys as ScubaToys, and I am sure they would be happy to give you their impressions of the visualator.
Good Luck!
Gary