Wrong! G-70 chord recognition is better then the others: it has several types of chord recognition that can fit different needings and keyboard settings.
It is able to recognize a lot of different types of chords and adapt the played styles accordingly.
As cgiles says, already G-1000 is comparable to (or better than) Tyros and Korg, and G-70 is much more improved.
Moreover I know that Roland has some patents in chord recognition techniques, and this could be one of the reasons why they work better.