I have a number of widgets on my nameplates - three labels, three progress bars, labels for floating text, icons, etc. This is part of the reason why I thought a panel per nameplate might be better. I was under the impression that changing a widget would invalidate the panel, so if I had 30 nameplates under one panel, a single (health) progress bar changing would require the panel (and all 30 namepletes) to re-process. I figured that at some point the drawcall cost would be outweighed by NGUI CPU cost for the invalidation.
In any event, good to know. Thanks!