I'm guessing from the question that you have never fished Arbroath area before. To be perfectly honest I would recommend fishing a safe mark (especially in darkness) which rules out the cliffs. The cages are not my cup of tea but can produce fish in the correct conditions/tides. Balleys might be a decent mark in the correct conditions. Im no east coast expert but the fishing tend to gradually slow down from now on, especially if these westerlies continue.
Fished the cliffs yesterday into dark- seven hours, not a sausage between us.
Try Auchmithie or the harbour if you're not familiar with the marks.
Ballys is murder now since they've added the rocks in front of the wall, you need to scramble up the wall and onto a real ankle-breaker of a pile of boulders to retrieve.
I do think, personally, if the council had poured concrete into/over these boulders they'd have a win-win situation. Anglers would have a cracking stance and the original purpose of the rocks (apparently to stop weans getting soaked with water bursting over the wall) would remain. You've also got to consider that these gaps in the rocks are gonna fill up with rotting seaweed and stink the town out to high heaven!