One of the reasons why I've never upgraded to 5.5 is because ICH10 passthrough was broken. Has that been fixed in Update 1, or is it still an issue?
I don' know about ICH10 but that has issue in NFS storage, VMware is working on this issue.
So I think, you have to wait for new patch or new release.
You can install ESXi 5.5 and apply appreciated patches on that.