hey what ya guys think of this?

Holymanta Adapters | Holymanta (http://www.holymanta.com/pages/holymanta-adapters)

It's a great idea.

But it depends on the quality of the ND's...

I love my heliopan, which is an expensive piece of glass.
If it would be integrated within my metabones adapter: perfect.
I already tried some cheaper ND's which didn't impress me at all. I won't put those in front of any lens.