In reply to oldie:
Thanks for the suggestions.
Yes, the Sub-C Rib route means descending, but it's only a 10min scramble back down to the Cwm Idwal path if I remember correctly.
Lazarus and something else (Groove Above, Arete Climb, etc.) would make sense. But, I've been trying to avoid Severe climbing for the benefit of one of my companions, who is resistant to the idea. This also puts paid to The Cracks and Slow Ledge Climb (VS), unfortunately.
By the by, I've done Central Arete and found the second pitch a bit of a horror show: a clean slab, with scarce pro and some very flaky rock or vegetated ledge shuffling to the left of that. It wasn't such a big deal, but I wouldn't rush back or recommend it to friends!