Lol, you beat me to the reply! Perhaps Siege, but without all those other annoying restrictions. Although, I did enjoy my time on Siege.
I've never been a big fan of merging shards. Personally, I kinda like playing on a dead shard; I hate fighting for a spawn, or dealing with all the noobs.
I still think they should bring some sort of way to quickly and temporarily transfer from shard to shard. Now that seems to be impossible due to the duping, but I believe your character being able to move around easily from shard to shard would be helpful. No bank transfers, no ridable transfers, no backpack transfers, just your character in its nekkid awesomeness. You can dupe nothing all you want.

Once they can get a handle on the duping situation, then perhaps be able to transfer what you're wearing/wielding.
It's working pretty well for Dark Age of Camelot, and it's a Mythic joint, so why not UO?