I think the new ribbontweeter of the outcomming Monitor Audio Platinum will outperfrom both. I can explain why.
The new ribbontweeter is bigger and wider. First of all it is opener than both the diamond and beryllium tweeter. I compared the Platinum with the diamond D2 and the stage of the Platinum is wider and deeper. Beside this the individual focus of voices and instruments is sharper.
The new one will have a lot more authority than the Platinum at this moment. We do a lot of research these days in sound&vision.
With the ribbontweeter you can create a holographic stage to die for. This is not possible with both of these tweeters. The stage is not only deeper and wider, but it can even create more space in front of the speakers.
I give an example: Miles Davis/Kinf of Blue. The piano on the right site owns the shape of a piano. The same about the drums on the right. It plays fully free beside and in front of the speakers. Also the presentation of the height of the cymbals is more impressive.