I would definitely recommend pursuing a diminished value claim. It is becoming more common now that people are aware of it. The process mat be time consuming, so keep that in mind.
Quality of the repair is key, so choose your repair facility wisely. If any cutting/welding of the quarter panels is necessary, this is considered "unibody" damage, and is what you should be most concerned about. Unibody damage is what most appraisers are concerned about, because they will disclose this at auction if they know what's good for them. It will almost always show on a Carfax report as well.
Good luck with everything, whichever path you choose.
For what it's worth, I would definitely keep the car for some time, the loss will be painful.