I switched from road BB5 to road BB7 relatively recently. When I first installed BB7 they felt very mushy. I also couldn't lock up my rear wheel. However, after carefully realigning them in accordance with manufacturer's instructions I made them work. No problems ever since, aside from occasional squeal.

I agree with previously posted advice: keep the brake actuator arm slightly pre-tensioned (despite the manual recommending to leave it fully relaxed).