Although everything you say is true, I'm not sure I'd agree. To me, one of the biggest requirements for a media center is a small power draw. It's an always on device that can get a lot of use. The fewer moving parts (drives, fans) the less power the puppy's going to use.
If you go back and read the build specification, you will see it list three 3TB hard drives. Which is why I suggested the platter based solution. But you statement has warranted an investigation of the actual power draws. So lets go head to head with the SSD specified vs my current favorite drive since they are in the same basic price range.
From the build: OCZ Vertex 3 MAX IOPS 120GB SSD - Idle power 1.65W, under load 3W
My favorite: Seagate Barracuda 3TB Hard Drive ST3000DM001 - Idle power 5.4W, under load 8W.
And you were spot on power wise. But lets look at the 5 year power costs just for the fun off it. As of Jan '12, the average price of a Kilowatt hour of electricity for the US is 9.83 cents (
http://www.eia.gov/electricity/). Since it doesn't hurt the SSD at all, lets use 14 cents per kilowatt for our math since that puts us at the top end average price.
Now for the number crunching. Lets use the worst case number of 8 watts and then percentage it with the other 3 numbers.
1000 watts / 8 watts = 125 hours of operation.
5 years = 356 * 5 * 24 = 43800 hours. 43800 / 125 = 350 .4 units of 1Kw of power
350.4 * .14 cents = $49.06
So SSD works out to $10.12 idle and $18.40 full load.
And the platters are $33.12 idle and $49.06 full load.
Now we could also take the time to look at the heat load issue, but for one drive to calculate the cooling required isn't worth it since we would also have to look at the heat load it provides during the winter. So lets call it a wash for now. Plus with the three other platter based HDs that are going in, adding an extra drive is moot.
So my suggestion adds $23 to $31 of cost over 5 years of operation, but adds another 2.8TB of useable disk space. Personally I would go for the disk space when looking at that cost because I would be able to store another 325 DVDs of movies. But that is just me being greedy
