IB folks, I've mentioned it before and I'll say it again:
If you really want to roll out a new feature, design, or whatever, please please please make them OPT IN instead of OPT OUT. Even if the new thing is going to become mandatory some time, it is better to let anyone who WANTS to try it out do so first, then push it to everyone later. This will result in much less flame headed your way when things inevitably don't go well in the rollout. At least if we know going into an experiment that it's an experiment and there might be bugs, we're more willing to work with you to make it better!
I'm sure, like many other posts in this thread, that this response will fall on deaf ears and you will never do it this way. But I sure hope someone will actually seriously consider this, because you're going to lose far more users than you gain by making (in my opinion) stupid decisions like this.