I'm looking at two characters: http://www.wow-heroes.com/character/
US Staghelm Sorrowsend GS 3975, live refresh shows 4307
US Staghelm Mithril GS 3767, live refresh 4158
So far so good, but when I compare the two using http://www.wow-heroes.com/compare/, Sorrowsend is listed with a GS of 4064 and Mithril has a GS of 3822.
So, what's going on? I'd expect the /compare values to either be the same as the cached data or the same as the live data, but it appears to be something else entirely. The gear changes that were made previously and were shown in the live refresh appear on the item comparison. The scope of the changes wasn't very large-- one piece for Sorrowsend and just a few enchants for Mithril, so I actually think the compare GS values are the most accurate ones, but I don't know for certain.