On a couple of worlds where I have been camping in low eras like EMA or even Industrial I got a couple of eras ahead on the map and it's causing me headaches as I don't want to age up. When I get quests that need me to acquire sectors, I can't do them - either I don't have the goods from the higher age where I'm at on the map, or my troops are too weak against those on the map.
On the other hand, there is a guide on the forums that shows you how to get a handful of troops from higher eras, it needs a combination of doing map and story quests in the right order, a fair bit of work to do it, but as a game strategy, if you can follow it correctly, getting those advanced troops can be quite nice (as long as you don't let them die...and then you've done all that work for nothing, or be willing to spend diamonds to revive them)