Just received my Omas Arco from rroossinck and if rroossinck is ever selling something you want - buy it!
The pen is even better than I imagined

The photos were great, but the reality....

I've just put some Herbin Lie De The inside (the perfect colour for an Arco) and written a paragraph. I'm not a normal Medium nib sort of guy, but in the Arco the ink just glides out of the paper and flows onto the paper.
The seller? His communication throughout, his letter, and his updates are all more than I expected. I'll do the review once my feet have hit the ground.
Grail is the wrong word, the right word is - Arco!