So Kerkythea, of course, has really become two commercially-available programs; Thea Render and Twilight.

Twilight is available really cheap for $95. It's an SU plugin which is perfect for SU users. They don't give too many details on their site as far as features or performance, but it does employ an unbiased Metropolis Light Transport engine perfect for internal and product scenes.
I am not aware of how advanced its material editing capability is but I assume that it's comparable to Kerky.

Thea Render is available for $215 (€195) and also comes as a SU plugin but their Studio version looks pretty nice, which is great for just doing work out of Moi.
It believe its "TR2" mode is the same MLT BiPT engine. There is something mentioned about being able to use your GPU to speed up rendering as well.
I'm not sure if its materials are the same as in Kerky with the ability to intermingle layers of material instances. They say they have "displacement" which is awesome! That's one thing I like about those V-Ray materials. I need to find a very in-depth Thea materials guide to feel good about it, though the interface looks very graphical and intuitive.

Did someone say one time that you could rent out render farm nodes? Well that's beyond my scope, but I do have to upgrade from the free app sooner or later.