I am also running an MD3000i on vsphere 5.5 without any issues. Currently my vmware cluster has 2 vsphere 4.x and 2 vsphere 5.5's. I just added the 5.5 servers last week.
Firmware on the MD hasn't been touched since installed 4 years ago.
| Current configuration | |||
| Firmware version: | 07.35.22.61 | ||
| NVSRAM version: | N1532-735890-004 | ||
| EMW version: | 03.35.G6.50 | ||
| AMW version: | 03.35.G6.50 | ||