I'd reject it based solely on the lack of dynamic lightmaps.
I could retort that all other engines are rejected solely on the lack of Geo-Mod.
Dynamic lightmap problem has posed a non-issue, I've figured out ways of doing realtime lighting effects that look good and are dynamic. Similarly the geo-mod limit is a non-issue. Both needed some creative table tweaking on existing things *cough* gun shot glare for dynamic lights for instance, etc., but works well. It sounds crude, but as I've said before, Volition is very good at small bits of code that seems like minor things turning out to be able to be usable for big features.
Also on how FS:FPS plays out, I'm hoping there's a bit of an S-Shock feel. The last mission should really get the feel that you're all alone in the dark, helpless, and freedom of motion is an illusion. (similarly with all FS:FPS levels they're intended to give a feeling of freedom, but you're really doing what they want you to do... sort of like SS1)