Vismat materials. Tips on seeing a preview?

I know some people have come up with some wild ideas on ways to see previews on vismat materials in your model but i have not found any techniques that really help.

I love the materials but i am hesitant to use them because i hate rendering to see previews.

Anyone have any solid tips that can really make these permanent in my collection?

I hate spending hours on a couple of materials and then just settling after being frustrated for so long.

Any help would be great!

Thanks all

-Greg-