aside from issues of feeling comfortable in close embrace, i think its technically more difficult. I had never had problems with the actual contact as I'd done other stuff before; but being grounded was something that took time to learn. I learnt tango in an open embrace then started close-embrace when I was learning to dance milonga. I prefer teaching open with little introductions to close embrace as we go along. Otherwise there is too much for the leaders to cope with, in my view. But I know teachers who are successful in starting with close embrace. For those who make the transition I understand that its harder going form close to open but I have only what other people have told me. I would talk to your teacher and say you are finding this difficult and are there other ways he can help you collectively as a class. Sometimes the problem can be one of commuinication. There are things I can do as a dancer that I find difficult to teach because I've learnt them intuitively; so I have to take step back and actually analyse what I'm doing in order to break it down. If you don't talk to him he doesn't have an opportunity to improve his teaching. I always watch how other teachers convey learning tango; and there are many ways to skin a cat.