As BB said guys' groups have always been open, I think it works better as you get a) people who have been on it longer than you who can give you advice, and b) people who are new and who you can advise......unless you are me, in which case you are the "oldest" in the group by about 15 weeks! lol
From reading on here I can understand why a lot of people would prefer the closed group situation, but I think it is important to remember that you are doing this thing for YOU; I honestly think if you rely on your group to get you through it then when you leave the program you're going to have a far tougher time than if you accept, from the start, that it's you and only you who can do it, and no matter who else is in that room for an hour each week and no matter how well (or badly!) they've done, you are you, and you weight what you weight, and you've lost what you've lost - and that's all there is to it.