May be he doesn't know something? Elon several times praised Merlin engines - which are certainly quite impressive. But he seemingly omitted some other rocket e

May be he doesn't know something? Elon several times praised Merlin engines - which are certainly quite impressive. But he seemingly omitted some other rocket engines which were technically even better. He's very good in delivering - and delivering a lot, but I think he still promises even more. And that's not too typical for engineers.