Alternate FR driver for the MJK OB design?

Now that the Fostex FF85k driver has ceased production, has anyone considered utilising the Audio Nirvana "Super 3 Cast Frame" full range as a substitute?

The specifications are here: www.commonsenseaudio.com/an3cfspecs.jpg

Has anyone tried them in the MJK OB design?

Any comments on their likely suitability, say compared to the FF85k, or now the FE103eN?

cheers

Doug