If you want to help your wife to get the feel, I would definitely go with the keel version. Simply because when she is gonna step aboard the boat will feel more stiff end the sailboat will feel less tippy (before you raise the sail).I'm not familiar with those sailboat but you might have more interior space with the keel version cause you won't have the centerboard trunk in the cockpit or cabin.
Even with the small keel, when the wind will be stronger, it will get exiting.
Now if your thinking to single hand your sailboat that extra 250lbs down below will be welcome because your not gonna have anyone else to sit on the rails...
I once when out with my small nordica16 singlehanded and I sailed around with a friend who was sailing in a small victoria18. They were 2 in the victoria. And then the wind got up, they were heeling just a bit(they were both sitting on the comings) while I had the rail in the water the hole time, some time i had to let go the main sheet... oh yeah and i had no place to hove to to take in a reef cause we were sailing in small channels... It was fun anyways
Welcome to sailing and sailnet, and have fun learning the ropes.