lol, the lip-synching topic again...
i think if you're in the music industry, you should sing live. i understand if you can't do it all the time, but i always prefer live over lip-synch, no matter how horrible you sound. there's emotion in a live performance that can't be expressed when you're singing a studio version of it. live performance =/= studio performance.
for example, i 100% prefer KANJANI8's "Eden" live over studio. same with Lady Gaga and "Speechless" (or any song, really).