We went with FusionIO cards also. We were getting 950MB/sec with 0 latency with SQLIO from the Fusion card on the ESXi host. Epicor was still slow with the entire SQL 2012 VM on the Fusion card. We had our APP server on our HP P4500 SAN and they suspected that was why. After moving the APP server off the SAN onto the Fusion card with SQL, there was no change in performance. Epicor is set to do "performance tuning" this week.
Our ESXi hosts are HP DL380p Gen8 E5-2670 with 256GB RAM, we have 3, but they are not dedicated to Epicor, but still have extremely low utilization. We have worked with HP Storage, and VMware, and we have no issues on the hardware side, but do have 1 test left to run on the SAN to look at the latencies with IOmeter.