DM600 <- cheap, small, no display, 1 cardslot, can be fit with a 2.5" harddrive. 1 Tuner
DM7020 <- large, 2 cardslots, 1 CI, 1 CF, display, 1 Tuner, can be fit with a 3.5" harddive
DM7025 <- large, expensive, same as 7020 but with 2 (exchangeable) Tuners.
DM800 <- same as DM600, but with OLEd display and with DVB-S2 HD support
DM8000 <- a DM7025 with DVB-S2 and max 4 tuners. (and IMO not worth the momey)