Took the xm4's on a flight recently and the ANC surprisingly works pretty well with drowning out engine drone noise. It's not quite as good and silent as the over ear counterparts like my WH-1000XM2 but good enough. With music playing I found them quite enjoyable. These are actually my favorite sounding Sony headphones so far. The others I've tried were all V-shape sounding.
Although, the sound quality is quite good and engaging from the xm4 (through LDAC) it's still just a smidge below something like the IE300 in terms of resolution.
While sitting at the airport I preferred listening through the IE300 as it's passive isolation worked well for noisy/crowded environments. And more comfortable for longer sessions.
During flights I feel like ANC is a must since passive isolation is never enough no matter how good a seal or deep you insert them.
As an overall package though, the xm4 is highly impressive. From packaging, to build quality, tips, app. Whole experience is top notch. Sony sure knows how to make great products. The sum of its parts make it my favorite TWS purchase to date.
Edit: I'll also note that LDAC cuts off frequently in busy, crowded environments like the airport and gym. I'm stuck with using AAC for stable connection. So not perfect, but sounds great when it works.
