We used online check in for the first time just a few weeks ago and while we didn't get our request initially, I asked the CM and we were able to be moved. Wasn't a problem at all!
I used it for the first time last month and didn't get my request. In the past when I've done check-in at the desk I've always gotten my requests IF I had any. Usually I don't but every now and then if I'm traveling with someone there may be one.