Chess 2 crams too many 'novelties' in the game, for my taste. And I am not convinced at all that each of them is an improvement. Like you, I am very skeptical about this 'dueling' stuff; it completely changes the nature of the game, making it resemble a lottery more than a serious mind sport.
I also have severe doubts about this mid-line invasion rule. It seems that this was inspired by a total misconception of the designer what Chess is about. Where opening theory in Chess is often criticised as being pure rote learning, end-game skill is very different, and in a sense end-games are the purest form of Chess. The mid-line rule does away with end-games as we know them.
Note that the idea of having different armies is not very new. Decades ago Ralph Betza invented a variant called Chess with Different Armies (see, e.g. http://hgm.nubati.net/rules/CWDA.html ). In contrast to the Chess-2 armies, which contain all kind of weirdness not seen in normal Chess, the armies designed by Betza consist of 'regular' Chess pieces, which just happen to move differently from the pieces in FIDE. A slightly more alien variant that employs unequal armies for white and black is Spartan Chess ( http://hgm.nubati.net/rules/Spartan.html )
I consider these variants better than Chess 2. They solve the problem of opening theory, lead to very interesting and challenging end-games, and do away with much less of what we value in Chess. Both CWDA and Spartan Chess can be played with WinBoard (against the Fairy-Max engine). I don't know if there are places where it can be played on-line. The Variant ICS at winboard.nl supports Spartan Chess, but there never are any people there.
edited moderator AndrewSmith