Well, the DS4000 is said to be quite decent and responsive, so I guess the DS2000 will be as well. However, the DS4000 still has some major bugs e.g. regarding cursor handling in zoom mode which make exact manual measurement more or less impossible at this point. So my bet would be that the DS2000 inherits a few bugs and introduces a few new ones and it will take the next 3 to 6 months to fix the worst of them (taking into account that the DS4000 is available for several months now).
Regarding truncation of measured periods: in manual mode, I'd say this is most probably just a GUI limitation and thus could be improved in SW. In auto mode, there could be a hw limitation as well - as the Rigol DS2000/4000 is very close to the Agilent DSOX2000/3000 chances are that they also copied the automatic measurement in the display buffer. Then again, the DSOX3000 measures at least with 5 digits, so there's a chance that the Rigol could at be as accurate as this - which would IMHO be satisfying for automatic measurements. On the other hand, as said before, the Tektronix DPOs truncate all measurements to three digits and obviously either nobody ever complained about this or they didn't care.
If there will be actually any improvement in the future is another question. I already tried to contact the Rigol support twice in the last weeks regarding this and other issues and I got no reply whatsoever. Not even an automatic reply. Furthermore there are no publicly available firmware updates. This gives me a bad feeling regarding customer support.