it's hard to leverage much weight savings using Ti versus Al.
That's what I've found with cooking pots. Ti may save you an ounce at most, at a fairly high cost, but should you want to do real cooking instead of boiling water, you really want aluminum which spreads the heat a lot more evenly.
I take a Ti pot for boiling water and an aluminum frypan for cooking fish. A Ti frypan just doesn't do the job!
My own experience with external frame packs is that they zig when I zag and throw me off balance. Fortunately, none of the resulting falls were serious. I'll never use one again! Internal frames move with me instead of against me. They can make an external frame pack out of unobtanium that weighs nothing, and I'll still not touch it! Your Mileage May Vary, of course.
ZPacks uses a carbon fiber frame for one of their cuben fiber packs. No, I haven't tried one. From the looks, it's basically an external frame pack and certainly lighter weight than my 29 oz. internal frame! It will lighten your bank account, too!