Unfortunately RCU 2.1 predates the release of View 4.0 (so View 4.0 isn't supported with RCU 2.1). The good news is that RCU 3.0 is in beta now and is scheduled to be released in late January/early February. RCU 3.0 fully supports View 4.0. RCU 3.0 will only support vSphere vCenter 4.0, but you're ESX3.5 will work fine with both.
Yes, the savings you see is the expected result. RCU uses File Level Flexclone to create the vmdk files for your new Virtual Machines. These can be thought of as "pre-deduplicated" copies of the original.
View 4 support with RCU 2.1 is experimental but there is a workaround for the issue you are seeing. In case you do not have access to now.netapp.com I've posted the description below:
Symptoms When running an RCU job that automatically imports the VMs into VMWare View, the task in vCenter never completes. It remains in "In Progress" status. In addition, the RCU service crashes. Despite this, the VMs are actually imported into VMWare View.
VMWare View import process from RCU does not complete successfully.
Cause of this problem This is a bug in the RCU code that imports the data into VMWare View.
1. Restart the RCU service with the following commands:
net stop netappVIPluginService net start netappVIPluginService
2. Cancel the task in vCenter using the VI Client.