It would still constantly remind me of what is missing. At first, I thought "well, we've flown aircraft without proper FMC in X-Plane for years", and not so many months ago I was still thinking "well, who needs a FMC anyway?" But then I used an aircraft which has a good FMC and it was a joy to use it and to observe the aircraft flying nearly perfectly the flight plan. So now I do miss it. The A350's FMC is so shiny and nice visually -- but totally lacks basic functionality (I would've never thought that I'd say something like this one day...). If I used X-FMC, I'd probably use it for all the other missing things, too (well... given someone created a good config file). I know the A350 will be upgraded at some day -- but until then, it's just a nice aircraft, with a lot of potential, but missing things and unpolished edges (such as many liveries which are not as good as they could have been with a bit more time).