Hi Josh,
Eloquence? Open-sourced? Owned by Microsoft? You're joking aren't ya?
Seriously though. The sad and sorry fact is, Eloquence, like Keynote, is a very old synthesiser indeed. With that in mind, due to its age, and the possibility that they probably designed it for NASA spacecrafts (Well, the price tag would certainly suggest it), companies whose prices and DRM policies are stuck in the 1980's are highly unlikely to jump to the 21st century and say, "Well, nothing's happening, let's just open source it". They'd be more likely to say, "Over my dead body". All that hard work for nothing, eh?
As for Microsoft owning it? That's a double whammy.
Firstly, unfortunate though the game of life can sometimes be, we have no choice but to face facts. The majority of TTS voices are now leaning towards a more so-called "natural" feel. This includes Microsoft, who have attempted to make all their voices sound natural right from the SAPI4 days. Sapi5 and OneCore are no exception. Personally, I think it makes it sound choppy, and lag like trash. So then, the only other option will be ESpeak which, while portable, responsive and open-source, as far as usability goes, sounds to me like a trip back to hardware synths of the 1960's.
Secondly, since Microsoft do a good job of butchering everything that they so much as walk near...No. The idea of Microsoft owning something as quality as Eloquence makes me feel sick. Several potential pages of Microsoft-directed rant suppressed, with great difficulty.
Put it this way. If I were any good at self-learning new systems, I would've switched to Windows 10 long ago. As it is, I'm still on 7. And there was me thinking that was too big a change when I was forced to upgrade from XP!
Cheers,
Damien.