I don't have a trip report, but there are plenty online on the ultra long range A350, as you mentioned, given its current status as the world's longest commercial flight. SQ departs from JFK and EWR to SIN, so either airports are fine, although I do prefer the ground experience at EWR to JFK. Not sure what the pricing would look like around those dates though -- still a bit too early to book, as WineCountryUA has mentioned. I do think you could probably do better than what you're currently look at with money + miles