M.S.
Well, I would just have to say that you just have to do what feels right for your family unit and don't worry about what others have to say. That said, I know that it is hard when family and friends offer their 2 cents.
My husband and I weren't raised in co-sleeping families but it works for us. My husband and I have 3 kids ages 5, 2 1/2 and 3 months and we all sleep together. The only reason they are 2 1/2 years apart is because my husband and I started having kids at age 37 and felt we were running against the clock. There is some jealousy but usually for my attention and it has not really been directed at a sibling. We have a king size mattress on the floor next to a double. The 5 year old sleeps in the double. We all get a good nights sleep and if the hubby and I need to be together we certainly spice it up and make it happen somewhere else in the apartment. We now live in Japan where sharing a room to sleep is the norm whether everyone is sleeping on futons next to each other on the floor or in a Western style bed. Kids stay with their parents until they are 10 sometimes and no one makes a big deal about it.
Have you read Our Babies Ourselves by Meredith Small or A World of Babies by Judy DeLoache and Alma Gottlieb? You can also check out the web site for Dr. James Mckenna who has researched mother/ baby sleep patterns. http://www.nd.edu/~jmckenn1/lab/