My sense is that the bolt-ons needn't go as tight as a typical QR. They are convenient to have for commuting when you don't want to worry about locking up your wheel.
But really, how much difference does a tight QR make in bearing adjustment? I've never heard of that issue before. Seems to me that if your cons are adjusted well and the nuts that border the cones are tightened against the cones, you've taken any play out of the threads and tightening the QR won't make any difference. Though I'd be happy to be shown wrong on this (and will have to start thinking more about how I adjust hubs when I overhaul them).
lawkd, I think that you're wrong about a hollow axle flexing when a QR is tightened. A hollow axle may flex a bit more (but hardly, since the middle portion of a rod plays a very small role in its flexibility), but it's not going to stretch or compress along its length.