Lollabelle - I am another mum that really likes the idea of having males in nurseries. My DD had a young one that was fantastic. He had much more nergy, and was much more fun that many of the women. All the children loved them! I think male and female do offer different things to kids, and ideally I would like my kids to have both!
I am not sure what is bothering you, but another way to look at this is that these guys must really like kids, otherwise as dommini connor says there is no reason why they would be there. So I bet they have to be better than average child carers.
Also, given my (limited) experience nurseries offer a much, much smaller chance of any funny business happening than childminders. Don't mean to offend anyone, but there are multiple staff, many rules, and no place where funny business can take place. So I really wouldn't worry about that!
Finally, ultimately you need to chose a child care arrangement that you are happy with it. everybody likes different things, and you are expected to shop and look around. So don't feel bad about visiting lots of places and asking a million questions. I think most reputable nurseries will actually require that you stay with your child for at least a few days. My nursery wouldn't allow me to just drop DC until after two weeks!
Good luck!
P.s. Dcs like nursery so much that use the threat of not taking them as punishment!
I guess that only says how bad a mummy I am...