I'm confused as well on ordering AoI. I'm afraid if I get AoI it will just sit around because others will want to play Brass over it. I purchased Age of Steam 3rd edition instead of Steam, which was the wrong move where my gaming group is concerned.
Why do you think it was the wrong choice? There are several strategies to getting people into AoS proper (beginning with anytime loans for the first two rounds, for example), and it's worth noting that the feel of different maps provides a lot of opportunity to get easier or more stabby.