The DG800 / 900 PCB even features the LAN connector, though at an awkward position. My bet is a slightly modified main PCB in the DG2000 with the USB host moved to the front, the LAN directly accessible at the rear and that's basically it. Rigol didn't even appear to have used the opportunity to beef up the FPGA a little so the frequency counter will operate in parallel with two generator channels -- the manual still states that CH2 gets disabled when the frequency counter is active.
IMHO -- this instrument is way too expensive for the performance it offers.