I have setup and installed Interchange with a PostgreSQL backend several times. There was a little manual handiwork that was required (due to pg permissions, etc.). In fact, I started playing with it when it was still MiniVend (if you look at the internal variables, you will see all the MV's referencing their herritage :-) ). It has really come a long way.
I have used, developed on, and administered massive e-commerce kludges such as Broadvision, and I have to say that I really like what I have encountered with Interchange. It's free, it's perl, it's fast and it's dependable. However, there are some things to keep in mind:
- You are going to have to learn at least some of the templating and scripting that they implement (even though you can write embedded perl).
- Interchange lacks some of the advanced features of the more $$ suites, including such things as (please correct me if I am wrong) connection pooling with Databases.
Also, I have only done 2-tier... I don't know how well it handles 3-tier/increased distribution/load balancing... I haven't needed that stuff for the small projects I have done - maybe you won't need it either.