Re: This is a 'how hot is hot' question
If I'm on the go, I'll mostly stream my music from home or have it with me. MP3 makes a HUGE difference in size compared to lossless, both in storage required (fits all on player or not), and bandwidth. And in 99% of the cases, I'm on the go (background noise) or at work (no HQ audio gear), so good luck hearing the difference.
Yes, I can hear the difference between MP3 and lossless, but it makes no sense to use lossless in many occasions