Huh, that is really interesting. I wouldn't expect a 365nm light to generate that much visible light. The one demo picture that Sunlite has on their website for the Slim UV gave me the impression that it was generating quite a bit of visible light, but given the overall awful quality of that image file I didn't take it for granted that the apparent amount of visible light was an accurate representation. It's also my understanding that a digital camera may make some UV light appear to be visible light. Based on your photos, the Sunlite does seem to do the best job of fluorescing the text, but I'm surprised at the amount of visible light.
I was also surprised with the amount of visible light and that is was white, but that said, it is not a huge amount of light, probably below 1 lumen.
My camera is a Nikon D300 and it has good UV and IR filter, but many camera's does not have good filters.
Do not expect the Sunlite to be the best light for everything, some stuff has better response with one of the other UV light.