It isn't *really* a problem for beat matching - after all you can just wait a second or two for the display to catch up and then adjust from there right. Or even yet not even look at the screen and do it by ear. But that isn't the point.
You are right in saying CDJs don't display instantaneous BPM on start, but that is because they are doing BPM calculations on the fly by analysing the track. You'll notice that the BPM changes on a CDJ as the music does, implying that its not a full track analysis leading to a single number.
Cross is slightly different. (from my understanding)
It pre analyses tracks and calculates a static BPM for the file. It then calculates the required tempo from the timecodes on the CD. The display shouldn't have to ramp up for Cross - it should be known as soon as the BPM from the timecode track is calculated. (which has to be in the order or 1-2 milliseconds since you have a 3kHz timecode track and you'd only need a handful of codes to determine the current cd temp). As soon as you know CD tempo, its a quick calculation to apply this to the actual track.
Cross must know almost instantly the timecode tempo as the sound doesn't ramp up to speed on play like a turntable would. (implying two different calculations for the "current speed") So why does the display have to be like that?
(of course if Cross is doing some frequency based peak analysis to determine BPM on the fly, then my argument goes out the window!
)