Agree that the non-HT CPU's seem to be kind of lethargic, but I have an exceedingly small sample size I'm working from in making that statement. But since you were suggesting it, ours is an an E5-2609 too, which seems to compare poorly against our common E3-1230's.
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3) Do not connect any ZFS pool drives to the LSI 2208 on the system mainboard. You already have a 9207-4i4e for that. I expect that'd be a reasonable choice but haven't actually used one with ZFS, but it's a 2308 based controller and I believe it can be configured to look like an HBA.
4) And now, for something clever. Omit the ZeusRAM you wanted to buy. Instead, buy the BBU for the onboard LSI 2208. Then attach the 2208 to a conventional hard drive sufficiently fast to handle your sync write load. The BBU plus cabling should be about $300. Now the thing is, by doing this, you gain a SLOG device that has virtually unlimited write endurance, and the latency of having the mpt driver shove data out to the RAID controller write cache is very low compared to having a write command issued and completion waited-for over the SAS channel. Bonus: the cache is MUCH faster than 6Gbps, so your SLOG device can accept the first NNN megabytes of sync writes at incredible speed.
I'm doing something entirely different than you, so I'll explain a bit first: we're using the 2208 with a pair of Seagate Momentus XT's in RAID1 for ESXi local storage and boot. Since most of our ESXi storage is SAN based, the 2208 is only lightly used. The system is slated to handle a bunch of VM's and then also a FreeNAS instance for general fileservice. There is normally no need for a SLOG device, but by just adding a virtual disk on the local ESXi server, I magically get this SLOG device with awesome characteristics... and since the 2208 is usually not at all busy, I get a SLOG device that can sustain almost 50MB/sec (craptacular throughput on the XT's) but bursts the first few hundred MB in a second.
