Thanks for the comments so far. I have a BTZS cloth too, and it does fine. Sometimes I almost feel it is overkill, as I have some pretty fast lenses.
I was thinking it might be nice to mitigate the geek factor of being under the cloth, at least in certain circumstances. Usually, I don't much care.
Looking at the photos, it appears a loupe might be a bit difficult to use with the open bellows, but maybe not.
I have to say, the version with the magnifier seems really appealing- you'd have a very dark area around the ground glass, plus a magnifier which looks like it can be "aimed" around. I'd love to hear from someone who has tried one.
I have a pretty nice Maxwell screen, which seems to be much superior to the Ebony version it came with, which was really not bad. Bill is a family friend, so I was able to trade some computer services for the glass- I think I got a good deal!