A good question... lots of time & money saved.

The return on investment in system engineering is difficult to quantify as it primarily involves writing clear and comprehensive requirements. While a team may be dedicated to this task, measuring the return on investment can be challenging.

The products developed in our company that started with DOORS requirements in the late 90s are now a one billion dollar annual revenue product line. My advice on requirements management in a regulated environment, is that if you try to do it cheap, rather than efficient, your products will suffer during the market phase.

As the product life-cycle reaches maturity for a given project, the ability to re-use requirements, and their related data in other projects is very helpful. DOORS is also a great tool for discovering "orphan" requirements early in the cycle, as well.

The best money invested on a project is always on requirements engineering, and an ROI of 10-20:1 is not uncommon.

It's massive, as it's a contract requirement. DOORS v9.5 enabled us to satisfy all our customer demands with relative ease. Can't quantify the ROI in financial terms though.

The largest ROI would normally be achieved on bigger projects, but an ROI is possible across many smaller projects so long as consistency is maintained in terms of process and schema across the projects.

Things are delivered to the customer on time, with less mistakes and missing features.

Because this is an expensive solution, if you want to realize ROI then you have to use it for big projects.