I know a lot of people have used titanium actions and some are quite accurate. I have a remington version in 7-08 with a lightweight Pac Nor Barrel and it groups fairly well, However, that said, I am friends with a well known gunsmith that will not put together a gun for me on a titanium receiver. Now this gunsmith has put together 3 hunting rifles, a 284 win, a 300 WSM and a 338 win mag and all consistently put up 1/2 - 5 shot groups, With scopes, these guns weigh 7 1/2 lbs, 7 3/4 lbs and 8 lbs, so while all are not of the ultralight variety, they are not overly heavy. the titanium remington with scope is a hair over 6 lbs. The 284 has over 10,000 rounds thru it and is ready for its third barrel.
The caliber 6.5 PRC is a good selection for a your wife, however I would prefer a 24" barrel to take advantage of most of the velocity this cartridge offers. I have found remington actions to be as light and strong as most and they are readily available and not that expensive. Just my two cents