I found the following statement on the totalwar website.

"Religion - is now an important factor. Christianity has become the dominant religion of the Empire, but it’s your choice whether or not to revert to paganism in the hope that this will bring victory. Barbarian factions can convert, opening up new parts of the technology tree in the process."

It's the last part I'm interested in. Could this feature be modded to allow factions to assimilate the technology of other factions when they conquer them and/or their provinces? I'm not thinking of playing as the Borg, but it would be nice to access the technology of other factions. This would allow "barbarians" to take on more advanced technology, and also give factions such as the Romans a greater variety of auxiliaries depending on the provinces that they conquer. The website already says that barbarians can build expanded settlements. Any thoughts anyone?