Sampo make the DVD5000, Coby make the DVD4000, the hacks for the players are identical (both use a Mediatek chipset).
Essentially, the 4000 is a smaller player, otherwise they're virtually identical in terms of media and file compatibility.
That also means they share the same faults, particularly inability to playback seamless branching titles without a stutter (both audio and video) otherside of the branch.
Some 5000s have had earthing problems (small electric shocks to the user - not life-threatening but still not very pleasant !).
Not a great deal in it, to be honest