Maybe it is my sax background, but I love flat keys. Listen to almost anything that is in Bb, then move it to B. Bb is a great key, but B is the thinnest sounding of all keys.
Guitar players these days can't play flat keys, so they need to tune down. I would prefer they did over bringing everything up a semi-tone. But that is just me.
this is entirely false bro ...sorry, been singing lead and backup in bands for years ....a 1/2 step on a whole set is huge ..but yes the break is mostly noticed on tough tunes and can cause some lower tunes to have less power in the low range.
this is why country artist use capos and odd guitar keys so often...cause they are trying to find the 'perfect" key for the voice....
now if your band writes tunes in Eb tuning and the singer still pushes himself hard then he's got a rough road ...
but a whole set that is normally mostly in standard down in Eb ....big relief on the voice!