Proac 2.5 Response tweeter upgrade with Ribbon Tweeter?

No idea on the matching, but I owned a pair of 2.5 and now own the D40r with ribbon tweeter. Much better speaker.

@jperry 
Thank you for your comment.
I love my Proac Response 2.5 speakers but would like a little more 'body' to the sound and deeper bass. I'm also very interested in the ribbon tweeters that are said to be much 'sweeter' and extending.
Could you comment on these and any other differences that you experienced when upgrading to your D40r's from the 2.5 response's?
Thx so much, 

At their best, ribbon tweeters can supply amazing, effortless, shimmering highs.  I'm definitely a fan.  However, ribbons' native impedance is usually so low that they need especially careful integration into the rest of a speaker system.  Often a conversion transformer is required, and the crossover(s) also require intensive analysis. 

What this means is that it's next-to-impossible simply to switch out a dome tweeter for a ribbon in an existing speaker.  You're much better off selling those speakers and purchasing some which have a ribbon already integrated into their configuration. 

"more 'body' to the sound and deeper bass"

It looks like you are using a tube amp with medium to low power. The Proac 2.5 is very inefficient, but can produce deep bass (see the review in Stereophile). You should borrow if possible a fairly powerful solid state amp (high damping factor and 100-200 wpc)  to see how that works with your speakers.