Very few responses on this. Mirrors my Google searches. I couldn't find any useful vacuum frame-specific hits there either. Not surprising, as it's a high-end, expensive item. But there were quite a number of satisfied customer testimonials for the UV light boxes.
The frames appeal to me as they appear to be relatively small and portable. At least when compared to those Nu-Arc monsters. I don't have that level of space, or need. These appear to be usable directly undernearth an enlarger for projection speed papers.