So after some testing and some research I am in this point:

The only valid command for creating images compatible with ESXi 5.1.0 is:

boxgrinder-build myapp.appl -p vmware --platform-config disk_type:thin,type:enterprise

The disk is created thin localy. If I use

"-d sftp --delivery-config username:root,path:/vmfs/volumes/datastore1 --delivery-config host:myESXiMachine"

boxgrinder plugin archives in tar.gz and on delivery it unarchives it, but brokes the raw image (eg: a 778mb thin of 10g is transferred archived as 265mb and unarchived as 60mb and obviously does not work).

I manualy simulated the process and got the same result, tried the "-S" option on archiving on the linux machine (handle sparse files efficiently) but gets error on destination, the tar implementation on esx is not supporting it.

I found some work around: zip, but on destination the image is unarchived ?with unzip) as thick not thin (eg: on linux is a 77mb thin for 10g, tranferred as 265mb, unarchived as 10g). It can be fixed on destination:

vmkfstools -i myapp.vmdk  myapp-thin.vmdk -d 'thin' -a lsilogic # and remove the myapp.vmdk afterwords.

But what if the trandferred image would have to be let's say some 100g provisioned as thin?

One other solution would be implementing a plugin for ovf. (Isn't this becoming a standard supported? ) For this you have ovftools which handles the transfer correctly.

Hope I missed something and someone can point be to the solution for thin image transfer...

Andrei