You should use a combinations of both UDP and TCP
Example, for moving characters or updating animations or rotating, you can surely use UDP. However, in order to prevent bugs in there, you use TCP to start it (send the first values, like speeds, etc...) and finish it (send its final X,Y cordinate)
In case NO UDP packet (i dont know why, but whatever...) would have arrived, the character would teleport to its final destination. But it least it gets there, and doesnt get stuck in some wall, because it missed a "rotate to left" UDP packet.
Also, for RPG games, dead-reckoning isnt nessesary with MooClick. You can just sent values every 3rd or 5th of a second. Where you use the "ball movement" on the clients. So the ball keeps moving, even if it doesnt have any UDP or TCP input.
But let me give you an even better key to a good RPG based MMORPG. You do not move the character at all, remotley. What you do is you send your keyboard input to the client. Make an eventlist (a list box) where you save your commands.
Then, in 1 loop, if someone presses both Up and Left and Space, then those are qued up in your Eventlist. You parse the list into a string, and send it to the client. There you un-parse it, apply the commands, and do all the movement stuff there.
Afterall, what happens after a keypress, is always more then the keypress its self. So you just send your keypress command to the client. Using your own commands. And you only send this, when something changes.
I would suggest to capute KeyUp and KeyDown same for mouse. And thats basicly all you need.
Having fixed that, you have plenty of available bandwith to take care for NPC's, bullets, etc... which ARE supposed to be controlled directly, as they are automated. But the best thing, is to make 1 client, a robot client, which is in fact the NPC / Bullet server, which is always logged in to the main server. It doesnt control players, but NPC's and bullets.
Most important thing here is that you will do collisions in the robot-client to, cutting out all lag and synchronization issues.
Ofcorse, when talking about MMORPG you >>ARE<< required to have a dedicated webserver in a datacenter with at least upload speeds of 10MB/sec. If you control NO npcs, bullets, or less then 15 players. You could try hosting a server at your home, but would still be a bad idea.