Just posted this on another thread, same subject - I really recommend the epi-no!
I know this is an old thread, but used an epi-no prior to having my baby in April 08. It works. I had a tiny tear, no need for stitches, and he was HUGE.
It really helps you to visualise the crowning and last few moments of delivery - very hard to do otherwise, and definitely not something your partner can help with. My sister used it for her second, and she had no tears at all - and my nephew was even bigger than my little boy.
She reported a certain amount of marital disharmony over the whole perinneal massage prior to her first, so was thrilled to be able to avoid it second time around. It is expensive, but from the prolonged discomfort experienced by friends who either had an epesiotomy, or a bad tear - very much worth it.
a tear or epesiotomy was the one thing I was worried about before birth, and I'm sure using the epi-no helped me to avoid it. DO IT!