Lynn, you know my thoughts, but here goes my 'discourse'.
Rituxan is a chimeric molecule, in that it is not fully human, part of it is actually derived from mouse protein. That being said, it was my first choice when offered Rituxan or Orencia. Rituxan is administered for the first time, then another time 2 weeks after that, and most get relief for 6 months or more. In my case, I was highly allergic to the stuff and had anaphylactic reaction (couldn't breathe). So on to Orencia. With Orencia, you have to get infusions monthly. Most start getting a response in 2 or 3 months, it took me about 6 months before I started feeling the difference. I had to rely on prednisone for relief until it kicked in. Now, I get pretty good relief for about 2-1/2 weeks after the infusion, and then its downhill till the next one is due. Orencia is not dosed according to body weight per se, you do get a higher dose if you are over 200 lbs, but it is a standard dose for up to 200 lbs. They've found out that people who weigh more than 150 but less than 200 often do not get relief for the full time in between infusions. So, I guess I could lose weight and thus, effectively increase my dose.
Anyway, given the choice between the 2, I'd opt to at least try the Rituxan first. I have also heard that soon a version of Rituxan that is not chimeric will be available, thus lowering the risk of allergic reactions...
There's my '2 cents'!!

When I had been through Enbrel, Humira and Remicaide, my Rheumatologist leaned more towards placing me on Orencia first as opposed to Rituxan. So far the Orencia has been holding me and I have been on it for the past 2 and 1/2 yrs. I believe I started noticing a difference in how I was feeling after about a month or so. Sometimes it holds me for the whole time or longer (5) weeks when I have to miss a week due to a cold etc. And then there are times when it doesn;t hold me for 4 weeks and everything hurts especially my legs and knees.