grouping by epic is powerfull but the estimate shown in the epic summary(expand an epic and you see an estimate value) shows only an estimate field. Trial an error learns this is the total original estimate.

first of all, changing the name to 'original estimate' would make things clear.
Second, this is only is not useful as the remaining work is what counts to see how much work is left.

I worked around it by using the REST Api to get the numbers myself but having this fixed in greenhopper would solve the problem.

Please add a remaining field or change the existing estimate field & change the 'estimate' field to 'original estimate'.