I don't have a lot of personal experience with RUP and especially not for software medical devices but I understand its intent. RUP was acquired by IBM last year. It is as much a document control and change control system as anything else. You can use it to record your user requirements, track change management requests, record defects and corrective action and trace the problems back through the development process.
It requires expensive licences, training, dedicated administrators and a lot of policies and procedures to fully implement its use. It also requires management committment in the same way that ISO 9000 does. Without it, RUP will just become a sink hole for money. Properly used it could provide a way to improve your software development system.
Hope this helps.