This is just the point. Will Miers be a rigid constitutionalist? I certainly hope so. If she will be, this is a change from her history in the late 80's and early 90's. But then again, that was a long time ago. It really does boil down to whether you trust Bush to be a true conservative. On many issues and decisions of Bush in the last five years, I have been disappointed.
But you have not been disappointed in regards to judicial appointments. Everything else is irrelevant to this issue. Bush has consistently appointed those who have a philosophy of judicial restraint. There is no reason to believe that he would change that when it comes to high court picks.
Yes, I would have loved to have seen a knock-down dragout fight with the Dems to get the debate going again on judicial restraint. Ask everyone else here supportive of Miers. They will say the same thing. But, you must realize a couple of things.
First, Bush has never been much of a partisan warrior. That's just not what he does. Think about it. He may play rope-a-dope with the opposition sometimes (and maybe he's doing the same with this pick), but he doesn't start fights for the sake of starting fights. If he did, the Dems in Washington would be a party practically neutered, even more so than they are now.
Secondly, if he did nominate Owen or someone like her, the Dems would fight and filibuster, only this time we'd be powerless to stop them. A couple of weeks ago, half of the Democrats voted to confirm Roberts. If an Owen were appointed, they would claim that they were reasonable with Roberts, but this pick was "out of the mainstream". If our guys tried to go nuclear, they would be painted as being the "mean" ones, and just enough RINOs might switch to beat the rules change.