Matt--
Still no inkling on what's happening with those "no show" files, and MC is still doing it. I will keep mixing and matching settings and hopefully something will eventually squeak.
As for using the handheld interface as a backup manager, the results are positive but not overwhelming, IMO. Everything in HH is tuned perfectly for uploading and managing small devices, and using my ipod with MC is a breeze. But for backups (an unintended use), the automatic culling of duplicates is a pain.
The workaround is simply to create multiple virtual devices, even on the same volume, which can then handle the orphaned dupes. This is a bother, but the ultimate goal is to maintain data fields in my library which account for each backup location of each track, independent of it's folder/tree location.
This brings up another difficulty, which is that in order to perfectly identify which tracks went into the device (given dupe culling and no-shows), you have to start a second sync, and use that info to tag the original library tracks as to which of them made it into the device.
If somebody's got a better, simpler way to do this, I'd be grateful to here about it. But even as it is, I think this method is superior to copy/paste within windows explorer, or using the "copy" function within MC, which is stunted, IMO.