Foren / Cotonti / Skins / Blackgrail vs Cononti

No, you need a lot of copy-past to have ALL features of Cotonti.
Sometime it is just a small change. One word, a tag, ...

eg: Subforums, Tags, ....
Indead it works without, but you have not all benefits of cotonti.

If I was you I would check it. A lot of work now (not that much), but will save you a lot later on.

If you need all the difference? Check the sed-light from Seditio 125 and Cotonti 0.5.0.
In unix it is only one command to check it.
You will see a lot of changes.