Yeah....search on that topic on this site and find that there is broad disagreement about the need for a keel.
So...from my perspective, a keel is a barnacle on the balls of progress. It impedes the ability of the paddler to steer the boat with their paddle strokes. In river paddling it can catch on rocks when you are traversing lines and can dump a boat faster than you can blink an eye.
I am not in favor of keels on canoes...except perhaps a shoe keel like those found on some Canadian canoes. The shoe keel is a lower profile and less obstructive to paddling and less likely to catch. Keep in mind that a canoe canvas is supposed to slide over rocks and logs if you encounter these...the keel prevents this.
So, my rule of thumb..for a restoration I generally put the keel back on if there was one in place originally. I may modify it to lower it's profile but generally it goes back on. I hate poking all of those holes in the canvas..but bedding compound should prevent leaks..
For a new canoe build I chose not to install keels....
For a beater/user boat restoration that I plan to use for tripping, no keel...
In your case, the loss of the keel and whether it matters or not depends upon how confidant you are as a paddler and also which OT hull you own. Some models track better than others. Some hulls are very flat bottomed and don't respond well to a paddle. Some hulls have nice high ends that act like sails in a wind. Whether it would benefit you to have a keel will also depend upon where you use the boat (and again, your ability to paddle). If you are dipsey doodling around in small ponds your needs will be different than if you strike lines across big angry lakes....
More than likely it can't hurt to put one back on..
Finally, in my opinion a keel (except possibly a shoe keel) does next to nothing to protect a canoe. It's more likely to contribute to broken ribs and cracked planks if it catches on rocks while you are in river current.
The stem bands and careful stewardship protect the stems..
Edit:
I just read this interesting blog post.... Mike pretty well hits the nail on the head. And as he notes, those of us that prefer working canoes are used to keel free hulls. He also draws attention to hull length.... hull design contingent, short boats don't track well...
https://canoeguybc.wordpress.com/tag/keel/
