I'm pretty sure Slopey arete starts off the two crimps and a low left foot. Then slap your right up onto the first sloper. Re-arrange feet underneath arete/roof. Get left hand up to next sloper. Bit of adjusting around and then try to mantel it out.
When you say dubious, do you mean harder or softer. Felt fair enough to me. No real tricks to it, just a bit of thuggery.