Thanks. I must say it would never have occurred to me to look to Bridge for this.
I don't see a Sync button. Where is that hiding? I did find a way to do it in ACR though. On the little bar that tells you what panel you're in — Basic, Tone Curve etc. — there's a tiny little arrow on the right that takes you to a little dialog where you can select, among other things, "Image Settings," "Camera Raw Defaults," and happy day, "Previous Conversion." That last one seems to dump the adjustments from, yep, the last conversion.
I think I'm going to tackle LR next. I've used C1 for years, and I like most of v5.1, but I don't like its noise reduction treatment of high ISO images. ACR 6.1 and LR3 seem to be far ahead in that respect.
Nill