you may be interested in something like SvSAN, we did a FAQ comparison recently against VMware all directly against the VSA FAQ. I think you will find all the information you need about VSA within as well as SvSAN.
http://communities.vmware.com/docs/DOC-18173 Contains a side by side and a link for FAQ. I believe there is a change to the VSA relating to RAID which is not updated in the FAQ or side by side.
SvSAN allows any host outside the cluster to access the storage,based on the ACL's and IP's set.
Thanks
Steven Santini 
