"#1, if your application follows proper data integrity practices (fsync et al)"
And if it doesn't happen to? How many filesystem users do code audits of all the programs their organizations runs, specifically looking for good practice regarding fsync? It's much better to just use a reliable filesystem.
"and your storage is properly configured, you will not lose data on a crash on xfs."
That's reasuring. I note that your recommended finger-pointing re: data loss, is now distributed between user and vendor. But it's definitely not XFS's fault!
"Losing buffered data on a crash is expected with any filesystem,"
No. Losing data on a crash is not "expected with any filesystem". (I've never had a customer quiz me as to whether lost data was "buffered" or not.) EXT3 was rock solid before they ruined it around 2.6.31 or so in the name of performance. A manual adjustment to data=journal should still restore it to its former glory. Though I fear that this new "performance over reliability" mindset in the Linux FS world might be eroding it in other ways, too.
"Ext3 tended to push data out more regularly"
EXT3 tended to keep your data rock solid safe.
"which had its pros and cons"
If I sent out a survey to my customers asking their opinion on reliability vs performance on filesystems, I already know what they would say. Reliability over performance: 100%. Performance over reliability: 0%.
It seems to me that, these days, Linux FS devs either live in ivory towers of performance benchmarks, or in California prisons. But none seem to live anywhere near me. We need more Stephen Tweedies.