I read the pro's & con's of both sides and I've been happyly downloading mp3s quite a while - BUT I'm not happy how these mp3's were EQ'd.
You won't be able to tell if you don't know both versions so here's a spectrum analyzer shot of two versions as 2 layers.
the opacity is set to 50%, so the darker spektrum you see is my unequed version of Sad sad sad,
the lighter one shows Vancouvers more High's - less Bass EQ.
you may get the general idea of what you're missing when not going for the flac version.
note: I tried to capture both audio events for the same song position, 3rd Chorus (which is quite impossible per hand)
but have a closer look at the slow decaying dots, outlining the spectrum.
Now if you try to reverse engineer the sound of an mp3 you will certainly have a loss of information.