people don't even need a recommendation anymore to figure out the best percentage.
Does the introduction of voting means that the current SpreadX11 format will change? Will there be backwards compatibility (i.e. will older miner programs work) or will this be a hard fork on all levels?
Practically nothing will change.
It's just an additional byte in the blockheader that miners have to set (and full nodes will expect), and it will have a default value preset for miners who don't care.
But the value will have to be there, because blocks without this byte will be considered invalid (since their header has a different length). So this will be a new protocol version and will require a fork.
Should be very easy to adjust mining software since SpreadX11 (both the X11-part and the Spread anti-pool-mechanism-part) stay exactly the same, just a new byte has to be introduced, and somekind of GUI or CMD input read in so that miners can type in or set their vote. (Or simply let them write in their vote in the conf file, and it will be used from then on.)
Right now I'm creating an experimental build for testnet that will allow us to CPU-mine and set our vote and observe how the percentage changes over time (1440 votes per day).
Should be fun. I hope to have it finished in a few hours.