Here's a suggestion.. why switch? Why not add.
I've maintained my 9001 certificate and added 13485. A single audit can cover both standards and may make sense even if you're changing your business to only deal with medical products. If you like your current system it shouldn't cost any extra to keep the 9001 part and have two certificates on the wall
It may appear like there's a conflict, particularly with 9001's requirement to continually improve and 13485's to just maintain but you can demonstrate each in different parts of the system (e.g. improvement in non-medical device specific areas, status quo with the medical products).
Good luck.