Fairly sure the cache is split between each core, hence double cache with double the amount of physical cores. In any case it wouldn't be...
Higher clock speed is more important than additional cores for Minecraft, so the latter's better.
It's a 6 month payment, not per month. Fairly reasonable considering how useful it is IMO.
Kimsufi 2G would do pretty nicely for purely backup purposes.
http://dev.bukkit.org/server-mods/logores/
http://dev.bukkit.org/server-mods/auto-shutdown/
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