Hi, quick question before I potentially break all my stuff. Does this support modded trains or is it purely vanilla rolling stock? I was hoping to use this alongside Schall's armoured trains & fgardt's flamethrower wagon, and cross-compatibility isn't explicitly stated anywhere.

Only mod that I've seen that DOES explicitly state it its Luzifer's "Quality Wagon", hence why I'm asking preemptively.

Modded trains should work fine, though you'll have to mine and replace them for speed/power scaling to apply. Wagon capacity should instantly scale to the quality-appropriate values.