I switched to flying US/AA pretty much exclusively in 2014, prior to that it was mostly AC for me. I may be an anomaly here, but I've never flown the 777 NGBC J or even Y on that plane- have only flown it in F, primarily between DFW and FRA. Having read reviews about the NGBC seats when switching from Air Canada, and being used to flat beds in longhaul J for several years, I did my best to avoid it. Can't say I regret it. The Flagship F suites were nice but the IFE was painfully outdated.
I've flown the reconfigured 772 many times in J and find the BAE product to be especially good- enough so that I don't miss the old F suite seats. Service and catering is about the same anyway.
Glad the old version is finally history!