Dell Poweredge r905 - Are quad opterons worth it? Upgrade or no?

Acquired a retired Dell r905 from a client, who upgraded to 2 hp dl580's, configured with quad 15-core xeon e7-4890v2's each.... o.O

The specs of the r905 are as follows:
- 2x Opteron 8350 (quad core, 2.0Ghz, 4x512kb l2, 2mb l3)
- 64gb registered ecc-ddr2, 32g/opteron
- 4x 600gb 10k Seagate SAS drives in raid5
- PERC 6i with 256mb of ram plus battery
- Dual 10g sfp card (proprietary pcie interface) - configured with 10g ethernet nics
- On-board dual gigabit ports, both DRAC capable (ipmi)
- Dual 1100w redundant power supplies, fanless
It's been running hyper-v with sql databases for the past 5 years along with 3 similarly spec'd, also retired 2u servers

The server is currently configured with 2 opterons, but it can support 4 if I were to get the cpu/ram daughter board pictured here:

The board would basically sandwich on top of the other two opterons, resting on the middle riser card.

Now, here's the question: is it worth it?
I found this board on ebay for $150 with heatsinks and shroud, and I also found a set of 4 6-core opteron 8439's for $200, and a 64gb kit of registered ecc ddr2-5300 for $100.

Total cost for upgrade: $450.

It really depends on your workload. Personally id save the money so I could switch over to a xeon based system since xeons pretty much eat opterons for breakfast :D

yup, this is my recommendation. hold off, save up, and move to Xeon.