I have seen one girl offering to use one of these. I am pretty sure they are very safe, especially for the guy. As for the female, I suppose it depends how careful she is removing it.
Even though I'm sure I read they are safer than normal condoms (anyone?) I think it puts me off because my head tells me that unless I am using a condom, it is not safe (Think Condom, always!).
Is it safe? Pretty Certain. Would I be happy with one on a WG? Really does depend. If it was a trusted regular that offered it after a few meets then I probably would give it a go, but for a first/one off meet, doubtful.
Probably does not help you at all, but there you have my thoughts on it
MC.