The Exmark 24-inch X-Series aerator should be available now. Check in with your local dealer, but you should be able to get your hands on one.
The advantage of the Exmark, when compared to your Ryan, is going to be dramatic. Being able to turn with the tines in the ground makes aeration a ton easier, and you can also run a ride-on sulky if you want to make it even easier. It'll make it way easier to get yards done...