nah. There's a reason why there hasn't been an outcry about 2.1 being "pay to win" outside a few sad cases playing semantic games on the forums: it isn't.
Sorry mate, but "expansions" arent pay to win at all. Every MMO or game with expansion has it, either you as a player follows with it or you dont. In WoW if you dont, you get left behind in anything and your char is completly useless if you dont buy that expansion.
Technically Sunleader is correct but it's not viewed that way by a lot of people as it's an "expansion pack".
The thing with other MMOs is that when PvP-Combat is involved (which is the root of the P2Win argument) they separate those with and those without. In WoW expansion packs tend to up the max level and introduce more power creep (bigger, better weapons and armour) However no one cares when it's PvE as you're playing cooperatively but when it comes to PvP-Combat then Blizzard recognised the obvious imbalance and split you you. It is impossible for a current max level 100 player to enter the 75-80 battlegrounds (old max level pre expansion IIRC) so the fact that these level 100 players have paid for the content and ended up with better gear they can't use it against other players. ED does not do this ... Unless mistaken the matchmaking system will lump all open players together : those with and without Horizons DLC. As such it's possible, in combat, to mix players with engineers mods (which they paid for via the expansion pack) and players who don't.
As I said though people don't see it as P2W as it's an "expansion" pack and forget you can be mixed with those that don't have it