thought I'd answer you back here about the omega 3/6 issues - the leptin thread is huge! I was surprised too because of the big fuss that most paleo people make about grassfed. The Jaminets don't make a big deal about it, they eat both grassfed and conventional beef. Conventional still has antibiotics and hormones, but personally I am not so sure that is such a big issue anyways.
What I saw was that since PUFAs are so small in beef compared with chicken and pork, really, you are doing well to minimize your fatty chicken and pork and eat beef. Pastured pork and free range chicken are better, but they just naturally have more PUFAs in their fat than beef does - but the pasturing gives a better O3/6 ratio. I tend to lean pork and chicken and introduce fat with beef tallow and CO.