Power CLI interesting interactions with Get-Datastore

Running 5.0u2

If I want to get a list of the datastores in a SDRS Cluster I get the values I expect, however when I select the value for GB it swaps?!?!?! :

$gDSC = Get-DatastoreCluster Tier1_DSCluster | Get-View

Get-Datastore -Id $gDSC.ChildEntity

This returns:

Name          FreeSpaceMB          CapacityMB

----------          ----------                    ----------

DS1             500000                    1048320

.....

This is when it gets weird......

$gDSC = Get-DatastoreCluster Tier1_DSCluster | Get-View

Get-Datastore -Id $gDSC.ChildEntity | Select Name,FreespaceGB,CapacityGB

I get this .....

Name          FreeSpaceGB          CapacityGB

----------          ----------                    ----------

DS1             1023.75                    500

.....

Can anyone explain this?!?!?!