Partly true; if there is "code" in the tiddler, it is not usable in TW5 - but e.g plain text tiddlers are OK, including CamelCase and [[spaced links]]. If I recall, also the text styling is the same. Not 100% sure.
Anyway, as you know there is also the less pretty notification that the tiddler is converted etc. You might want to still convert them to rid this and, after, remove the "changcount" field - but only after first tagging (or befielding) them all with e.g "TWC" so you can easily find them later. Currrently it is the 'type' field that causes that notification.
This should make CamelCase suppressable like normal TWC.
I made
Batch Manipulator for mass conversion. It would also allow you to filter out specific tiddlers for conversion (e.g by tag).
Remember to back up first, if you use it.
<:-)