I wanted to book a redemption for HND-LHR in J. There was no availability so I booked NRT-LHR in J, with the intention to pay the change fee and rebook onto HND-LHR if it becomes available.

In another post it was mentioned that the HND flight would be on a 777-300, while the NRT route would be on a 787-9. I'm flying next January.

Is there likely to be a big difference in experience based on the aircraft used? I favour HND as it's more convenient and I fancied flying this route as I hadn't flown it before in J (but have flown NRT in J).

Should I pay to swap to the HND flight on a 777-300 and the added convenience, or is the experience on a 787-9 (presumably fairly new) likely to make for a better experience? I've only flown BA dreamliners in PE.