I tend to trust Ridewithgps since it tracks my gps very well for rolling or hilly rides. Garmins don't do well on flat terrain since they tend to add up all the +-1 ft elevation changes. That having been said the differences between the two sites are very large given that they are all using the same raw data.
We're going to get in 50+ miles these next two weekends so we won't have any excuse for not trying the Century. Tomorrow we might not get too wet, but it's going to be windy for use.
It's interesting that the climbing shown on
www.bbcnet.com is 4950' which is not that far off of Ridewithgps. I wonder where that side gets its climbing?