Treehouse, I would repair it. Having a anvil in poor shape is like having half a anvil. If you following the directions Robb Gunther gives in this link and you know how to weld, you'll have no problems with the repair. These are the directions I used to repair mine. If you surf the net, you'll find a lot of folks warning against repairs, and talking about the horrors that can happen Personally, I think a lot of the myths about the difficulty of anvil repair are by folks that aren't trained welders.
Anvil Restoration