I can set aside the time to do this next week and I wanted to set up a new local instance anyway.
So as not to compare apples to oranges, how do you import the planet file on the official server? There are a number of tools to use with various options, not all of them allowing for daily updates.
Can you post the script for initial import and the one for daily/minutely updates? It'll allow me to set up a similar instance.
I'll then do a full planet import with and without hstore and time that. A few updates, time those. A few rendering jobs, time those. Might take a while to complete the benchmarking, obviously, but then we'll have a good idea of what hstore brings, performance wise.
This will be run on a AMD FX(tm)-8350, 20Gb RAM, on a RAID-6 array of spinning rust. It's reasonably performant, considering the lack of SSD storage.