Maybe this was posted somewhere in the 6 pages already but my opinion...is that mp3 vs flac doesn't even matter. It's so far down the ladder of mattering it's not even existent.
The super majority of music nowadays is so overly compressed dynamically that it's stunning. The details are ripped right out of the recording before it was even finished. Which is a shame if you think about the kind of technology available today.
The second problem is you actually need a decent set of headphones or speakers to judge these things. Which I'm sure the majority of people in general, perhaps not this thread do not have. Then on top of that, all the characteristics like frequency response or distortion are different in every system. You may not be able to resolve the detail differences in these particular songs on your system but maybe you could with different test material.
I guess my point would be...what does it matter if going to a well encoded mp3 lost you even 1% of the information from the original track. When depending on the music you're listening to or what you're listening to it with resulted in much much more than that.
Some of you may not fit into my generalization but I believe if there were a honest poll of material and equipment that the majority would.
This.
What pisses me off is we have assholes like Neil Young acting like MP3 compression is the problem. He even goes through and sets up a whole device and service, but it doesn't even address the real problem: the recordings are being ruined in the studio before we even have an opportunity to buy them. Who care is we get 64bit 512KHz if its screwed to the point that consumer level cassettes are technically capable enough to handle the actual end result?
I somewhat disagree with your second point. In the past few years headphones have come a very long way, you almost have to go out of your way to get bad ones. Even Bose and Monster/Beats have competent (if not spectacular and some still pretty poor ones) headphones that would easily show the issues if we had anything worthwhile to reference them against. They've gone back and redone a lot of the back catalogs so that they sound like modern methods so you can't even necessarily take older recordings and compare. Even the Apple earbuds improved substantially, and I know tons of people that have invested in better stuff.
I have some FLACs of some older Heart recording and it is mindblowing how even the low end just slaps the shit out of modern recordings. And its not like Heart was some bottom heavy sound. But the texture and timbre, with nice impact (but not overwhelmingly so) in those puts to shame stuff that is suppose to be "all about the bass". There is absolutely no reason whatsoever that modern recordings couldn't match and even exceed that.