What a controversial topic!
The baby caught a cold from his big sister which took a little over 2 weeks to shake and turned into a double ear infection. He went through about 3 or 4 weeks of not being able to sleep well which turned into won't sleep in his crib.
He is such a happy baby, so we were so surprised that both ears were infected. By the time he was on antibiotics for 7 days we were wondering if he was just so used to co-sleeping that he didn't want to go back to his crib or if something else was wrong. Once we got the all clear that the infection was gone we decided to sleep train to get him back in the crib.
Since he has never really napped in his crib, we decided to try to start napping him in the crib too. So how is it going? We are on day 3. First night he was off and on upset for about 40 minutes. Day 2 and 3 it was less than 15 minutes. I feel better about it now, but I still cringe when I hear him crying. While co-sleeping might be for some, it just didn't fit for us. We felt like sleep training was our only option to get our room back.
Next step - sleep training in the middle of the night so I can get more than 3 hours at a time!