A few things are already different.
More memory, more sample rate, higher DC-gain accuracy, higher timebase accuracy, larger screen, 50 ohm inputs, connection for active probe...
Whether this is worth 3000$ more, I cannot judge.
But how did you come up with this older scope series from rigol?
If it doesn't have to be MSO, but has to stay rigol, I would rather get a DHO4204 and hack it to 800Mhz.