Now I know the reason why when setting up a replica job the default disk type for the VM on the target datastore is 'Thin' (the assumption is your destination has less resources than the source). However with VMs I have manually changed to 'Same as source' I notice that if I go back in to edit the job, the disk type is still showing as 'Thin' as opposed to pulling in the actual value from the job.
The following picture should explain a bit clearer
The VM was set to 'Same as Source' but the disk type reverts to 'Thin' when editing the job.