+1 from me!
Time to bring some life to this thread. This needs to be implemented now more than ever, but imo, only for the GBs that donate goods directly to the treasury (Arc, Obs, Atom). These GBs are meant to help the guild, but when you're in a old world and everyone in the guild is at the end of the tech tree, the GBs only help that one era. This wouldn't be that bad if the new eras (AF and OF) had their own map... but they don't. My guild currently have over 100k of each AF good (other guilds have much much more) and we can't do ANYTHING with it (except open GE... which doesn't take anywhere close to 100k of each good). This makes the Arc, Obs and Atom next to useless at the end of the game.
Adding this feature would make it possible for guilds to go to lower age maps and lunch big campaigns. This would also add another fun new dynamic to guild management to manage what era of good it needs to fight or defend. And most importantly this will help keep GvG alive in older worlds.
I've read a few comments saying just build the era of good you need... This is true and works for low eras as the goods buildings are small, you can place enough to get the large amount of goods need to lunch a huge campaign (My guild was able to do this for LMA). But when you want to do this for let's say ME or PME, it's next to impossible to get the large number of goods needed. First you need to build the good building to get the secondary goods needed to make the actual ME/PME goods. This takes way to much space to produce so little, it's just not worth doing GvG in those eras.