It depends on what you mean by "compatible". There are several levels:

1. Cannot be mated at all.
2. Can be mated with adapters, but will be janky, wonky, and/or funky (e.g. single-bolt adapters twisting with heavy gear).
3. Can be mated with adapters, and is solid as a rock (e.g. two-bolt adapters).
4. Can be mated without adapters.

I know Manfrotto has items in the 2 and 3 category, but I don't know if there are any 1 or 4.