I posed that to the developers and received the following reply.
About RTX and the latest hardware. We do support the latest hardware obviously. However, we do not specifically use RTX for now. This is too restrictive in terms of hardware vendors. A scene rendered using RTX on a latest NVIDIA hardware will probably be hard to render identically on other hardwares that have no RTX, so that’s a clear limit in this proprietary technology.
In layman terms, RTX is only available on a NVIDIA video card. We want to ensure that our users, regardless of the video card manufacturer they chose, can have the best renderings.
Now the 1000x increase in speed. No. Not even close.
On NVIDIA’s website they speak of a 10x increase in speed and that is just on raycasting. Our rendering engine already takes the raycasting to the GPU. Renderings take two steps raytrace and radiosity. The increase in speed would therefore be seconds, maybe a minute faster and our raycasting already does that.