In case you were wondering why Deus Ex has a different model format than the normal Unreal/UT engine, it's because it supports a higher mesh resolution. That's not so important when dealing with weapons or a pack of cigarettes, but it may be something you care about when you want to have finer facial detail. Here's what I mean:
Here's the GM_Trench mesh (the one used for JC, among others) exported to the original Unreal format, using a utility called WOTgreal 2.013. I've hidden the glasses polygons so you can see the facial detail:
Now here's the same mesh exported to the "full mesh resolution" Deus Ex format with my in-progress extractor:
Pretty hard to tell the difference, huh? Yeah, me too. Once the textures are applied, I doubt many people would notice. So the difference may not be critical, depending on what you're doing. One thing that could end up being an issue is lip synching. Since you need to be fairly precise with that, you may actually need the full mesh resolution that the Deus Ex format provides.
Here's a shot with both meshes super-imposed. Pretty close:
In case you were wondering, the white lines represent the low res version and the black lines represent the full res version.