While the older 1.0 has seen huge success in competitive gameplay, it may begin to succumb to several decks in 2.0, namely the new Blackwargreymon and Phoenixmon decks. Blackwargreymon can cripple 1.0's huge reliance on tamers while Phoenixmon's sheer number of blockers can slow down offence, and the generic 1.0 deck may lack deletion cards to turn board state to their favour.
2.0 meanwhile can be tad too slow against many other decks, but trades off speed for better board control. This deck throws bigger Digimons at your opponent (such as DX and X7) and forces your opponent to react to them, and such decks typically can be more robust against a larger variety of matchups.
Personally I would feel that 2.0 frees up more deck space for cards that counter a variety of matchups, which is important given the many new decks and enhancements coming in BT-11 such as Blackwargreymon, Ulforce, Bagramon, and Ragnamon. A largely linear and predictable deck such as Xros Heart 1.0 may very well see its last days coming September end.