Being from both sides of this coin (as a player and dev on both) this matchup is so incredibly intriguing to me. Because as a number of Wizard101 players have stated across these forums, they're not wimpy, scared little carebears. In fact, I'd argue that there is a very large number of players from Wizard that are just as rabid and skilled as the many Shadowbane players here. I know that every last one of you Shadowbane players will feel scorned by this statement, but I've lived both sides of this and believe me, you're not going to be disappointed in the challenges you'll receive, should the many Wizard players feel like they want to stick around and be competitive.
Alongside that statement, there is also a much larger number of W101 players who don't get into the details and min-max their characters and just play for the sake of the story. I wouldn't expect them to have the same level of granularity and interest in trying to figure out every little nuance in the game to get that edge that I'd expect out of every Shadowbane player (and let's be fair, not all of us were that intricate with our character designs nor level of knowledge of how the game could be played).
And W101 players. You shouldn't take all of the Shadowbane player board warrioring to heart. Most of the time their forum persona is not mirrored in game. The in-game interactions were typically with the real person and the forum posts were typically in some sort of "character" if you will. They had to be strong and maintain their stance politically. "Politically" is used loosely here
In the end, I can see players from both games coming together to be competitive whether they join causes or fight against one another. And it'll be a blast! But, the most intriguing bit for me, personally, would be to see who would win. A group of Malistaire-slaying Wizards or a group of Shadowbane-wielding Minotaurs.
Let the fun begin.