Turns out the improved heat transfer argument for aluminium cases isn't all show no go. I unplugged my fan controller (that's all the case cooling) and popped the side panel back on, half an hour of BC2 later the entire case was steaming hot to the touch! I don't remember my old Chieftec doing that.
Same thing happens with my PC-Q08B, the side panel with the mobo attached gets rather hot to the touch, at least I know the heat's going somewhere!
Should put a huge heatsink on the sides or so. Maybe connect heatpipes to it like with that Zalman case