1. Stay away from DM800 Clones (there is a liklehood you will get a bum one)
2. TM800HD, I have also heard good things, it's open source (It's £50 more than the clone dm800). Sounds like this would be the one of my choice.
3. Vuo Duo + is dual tuner, do you really need a dual tuner. If so go for this one.