"I was given to understand that Kerkythea was evlolved into the GPU Based "Thea Renderer"

Thea is indeed by the creator of Kerkythea. He has stated that work on Kerkythea will continue. It remains to be seen when/if the announced update will show up - promising a 50% speed increase and  64bit support. As it stands, it's main advantage IMO is the ability to use different modes in one app - in addition to being a nice free renderer with good network render support. Its future however may have been sidelined by its commercial cousin. I see GPU support on the Thea roadmap but AFAI can see, not in the current version unless I missed it.

"Democracy is a pathetic belief in the collective wisdom of individual ignorance." - H. L. Mencken