I don't know what kind of Pixie Dust you are looking for but the online check-in and regular check in process are virtually the same once you are at the resort. Only difference is you stand in a different line (which may or may not be faster than the regular line) and you still hand over your license when you get to the counter. The CM will find your folder, activate your keys, and send you on your way. If you are having a celebration they will still know about it (I think there is a section in the online check-in page to notate it) and will hand out the appropriate buttons. As far as in-room stuff being done, I would think it is about the same since the front desk CMs aren't the ones to do it. If it is a birthday celebration the b-day card will still show up eventually.
For what it is worth, I don't find the online process that much faster than the regular way to do it. :shrug: