You can draw from the California experience where they have the three strikes and you're out. I don't know whether you could call it evidence, but there is a growing belief that when facing an accused charged with stealing a piece of pizza off a plate—it's his third offence and the judge knows if he convicts he's going to jail for life—the judge finds some way of seeing a reasonable doubt. Or if the judge doesn't agree with the mandatory sentence, he can rationalize, perhaps on the evidence, a little more favourably to the accused to find some way, procedural or something else, not to find him guilty.
That's another hurdle. Not all judges will see the evidence the same way. I think they're human and mindful of a minimum sentence, and they don't believe the minimum sentence should apply. The next thing you know you might have an acquittal, which is one other consideration along with the ones you mentioned about laying the charge in the first place or pleading guilty to a lesser charge.
So the path is strewn with problems.