Never heard of a Cleveland pear, but Bradford pears, Pyrus calleryana cultivars usually have leaves that are too large and don't reduce. Species calleryana (seedlings and cuttings from seedlings) however are quite nice. Small leaves, short internodes and nice little round 'pears'. The only problem is that seedlings are hard to come by, and they take eight to ten years to flower and fruit.
Since at the subject of pear, have you heard of Pyrus pyraster? It is a wild pear from Europe, small edible pears and a tough ancient plant that loves sun. It could be a great candidate for bonsai. I remember them from my childhood in Transylvania. And there is the wild apple, Malus sylvestris, another ancient species from Europe, with small fruits, perfect size for bonsai. Both can survive in almost any soil, they just need lots of sun.
I think they could be great additions to bonsai (incidentally, with high genetic value in this era of hybridization and domestication), but I have no idea whether anybody even knows about them here in the U.S.
I have heard of the pear, but have never seen one, or know how to obtain them. I have seen Malus sylvestris seed for sale. Both sound like excellent candidates, especially if they could be collected from the field. I have a small Asian pear that I got from Jim Gremel. It was supposed to be Malus toringoides, but turned out to have pears! We think it is species Pyrus calleryana or P. ussuriensis, or another small Asian Pear. This is one of my favorite trees and will be a stunner in a few years. It was field grown at Jim's place for about ten years and has a wonderful moving trunk. It should finish at about 10 inches tall. Trunk is done, just have to work on the branching. There are many species of wild Prunus, Malus, and other fruiting trees in the US that would make great bonsai. I am sure the same is true in Europe.