Long before I added north country canoeing to my slate of outdoor activities, I'd given away all of my external frame packs and gone to internal frame models.  For me, they offered the advantage of being closer to your body and less likely to tip you if your center of balance is not exactly right.

It was a lucky choice for me in that the internal frame packs seem to form to the shape of a canoe more easily than an external frame.  Furthermore, since I mostly paddle solo, they more easily fit into a solo canoe hull.  Generally, my objective is to have minimal (to no) pack profile above the gunwale line.  An external frame fits in very nicely in this context.

My most recent set of pack purchases have been along the lines of an internal frame pack, but with "waterproof" exteriors.  

Yes, admittedly, I have to dig to the bottom of the pack for certain things, but then I don't have exterior pockets to snag on things while loading/unloading or portaging.

dd