From what is sounds like then, either you will have to redesign your configurations as iParts in Inventor with a Custom Parameter column or you can start using Frame Generator. The biggest difference here will be that you will have a new file for every configuration member created as either a new part or a derived link to the iPart Factory. This will make electronic data management easer given you have individual files to track. If the majority of your configurations are structural steel (I know you used that as a simple example) then the transition won't be too bad.
What I would forsee is keeping your seat of SW around for older designs that need to still be updated using the original configurations, and new designs would use iParts or Frame Generator in Inventor. Just because you switch from one CAD software to the other doesn't mean you need to do it overnight, but instead draw a line in the sand in product development for new designs. In the end you will have a little bit of work setting up the way Inventor will do it, but there are some other factors here rather than just the up front work on the transition. For instance...
Do you want AutoCAD, AutoCAD Mechanical, Showcase, 3DsMax Design, Sketchbook, and Alias Design for free? WIth Inventor those are now part of the package depending on what Suite you get. If you are paying for an AutoCAD seat right now as well for any of your work you are potentially paying subscription cost on both ACAD and SW instead of one price for both which is about the same as the SW cost. If you are not on subscription for SW then you are not getting service packs for your product and are being left out of updates to the software even in the area of hotfixes.
I am sure what you are trying to do in Inventor as compared to SW is not that difficult to set up, but you should ask your reseller if they can show you the best way Inventor would do it and what advice they have with your business practices to help in the transition if you choose to move forward.
