The JD800 of course shares the basic architecture of the XP/JV series, so I don't think you will be disappointed with the quality and range of the JV1010, especially in it's price range. But the controls on the JD800 were one of it's biggest features, whereas realtime control on the JV1010 is non-existant without using an external MIDI controller. But in a home studio the JV1010 is hard to beat for the value it offers.
The closest successor to the JD800 in terms of synth architecture was the JD990 module which is probably just as hard to track down as the JD800. But worth buying if you can find one.