Both physical and virtual RDMs have experimental support in 1.0. By experimental support, we mean that the feature should work, but it has not been tested sufficiently for us to be comfortable with you relying on it in production. As a result, you should not use them with production SRM deployments, but if you would like to use it in evaluation or test labs and report issues, we will be happy to take those calls as eventual removal of the experimental label is intended on our part.
As for NFS support, I can tell you that this is becoming a common customer request. I can not comment on roadmap for new features like that in this forum, however. If NFS support is a major need for you, I would recommend scheduling an NDA roadmap discussion with your local VMware representatives.
I've done countless tests and failovers with RDM's and found it to be very reliable. Even if it doesn't work out - its a relatively simple task to remove the "bad" RDM and add it back in... the downside is the number you might have to do this. But like I said I've found this experimental feature pretty reliable...
I hope it won't be long before its QA'd