It won't do anything problematic to the LF performance.
Of a broadband trap ;)
Panel traps will be affected by absorbers stuck to the panel. Whether or not it's a negative will depend upon whether it was allowed for in the spec./design of the trap.
Yeah, I figured that. I'm going to go with a broadband trap design.
I have sloping ceilings on both sides of the room, and my mixing desk is mounted perpendicular to the slopes, which in that room is the only choice I have). I figure any attempt to tune trapping is doomed to failure, especially as I don't really know what I'm doing, so I'll try a broadband trap and aim to hoover up as much corner bass as possible...