Okay, testing on a Touch, kablooey!
Code:
140907:023456 cvm[1922]: E rc:lwsf:http_code=0,handler=process_/change,luaerr=LUA_ERRRUN(2):worker script failed: /usr/lib/ccat/change.lua:1371: /usr/lib/ccat/change.lua:1055: Attempt to set unknown field collectionDataSetName
So probably shouldn't set that unless FW >= 5.4.2

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EDIT: Followed by...
Code:
140907:023853 cvm[1922]: E rc:lwsf:http_code=0,handler=process_/change,luaerr=LUA_ERRRUN(2):worker script failed: /usr/lib/ccat/change.lua:1371: /usr/lib/ccat/change.lua:572: Attempt to set unknown field collectionCount
If you say so, mr firmware...
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Hacking those fields out works, I successfully reimported my moderately heavy db (~500 items), in 46.21s

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EDIT: Woopsie. Except the framework doesn't see anything inside the collections (although the item count is accurate). As for CM, it sees them, but refuses to open them (again, item count is accurate).
The journal shows that everything was imported with a null cdeKey & cdeType...
EDITē: Ah, gotcha. They were imported without splitting the legacy hash into two fields. Looking into it

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