A couple thoughts. First, I think Michael has illuminated several key points. Hopefully these will be reinforced by reading the books you have purchased.
Next, sistering and half ribs. Ixnay on thatay.....
Sistering makes a "hard" or fixed spot in the hull. That is counter to what you want to accomplish. The hull should be able to move and flex. Done properly, replacing or backside repairing provides a repair that retains the original purpose of the hull. In a newer canoe without real historical significance, I lean towards a replacement. It's pretty easy to knock out a few new ribs and install them. It's actually an enjoyable process. If a crack in the rib can be flexed open in a "standard" canoe, I'd probably replace it.
The backside repair allows the original rib to stay in place, but to do it overlook how much planking you need to disturb in order to do this correctly. Planking joints need to be spread out, not lined up with each other. When you take into consideration existing joints, sometimes this causes you to remove quite long sections of planking. Not that this is a problem, it's just a detail to consider.
Half ribs don't necessary strengthen a hull. They do make it heavier, and they offer some extra protection to the bottom of the boat. I like half ribs in a canoe that gets heavy tripping and poling use. I just do not enjoy the extra weight. I don't know (Benson?) the proportion of canoes with half ribs, but most of mine do not have them. Whatever the case, I would not think of them as a fix to cracked ribs.