The flight is a one-way avios redemption. IB IAD-MAD-VCE in Y at a discount in $ and avios compared to BA in IAD-LHR-VCE in Y. Although the option of IAD-LHR in PE is attractive. I'm not sure which is more confusing, the connection in T5 at LHR or the T4S-T4 shuffle at MAD. And since the A321XLR for IB is new, who knows what the Y seats are like. Google flight is saying 30" and not 31". That's a big difference for LH. Thoughts?