Where do you usually look for music? if you mean limewire, or a downloading client then obviously they will be there, when i say mainstream, i mean bands making appearances on telivision, and selling their album to any label that asks for it.
IT DOES MATTER if your music is on vinyl or not, bands who release music on cd have an easier way of showing off their music to people, and it leaves more options, putting out a demo over a 7" record isnt the best way to go if you want to make it big.
Screamo, Emo, Emoviolence, post-rock etc are all a form or sub-genre of emotive hardcore.... its basically the "metal" of sludge, doom, black, death etc....
Alright well after looking at a bunch of fan-made yaphet kotto myspaces, i found one that has a good song by them, listen to the drum intro, or the whole song if you want for
"The Fall"
http://www.myspace.com/yaphetkottomusic
and check out Neil Perry, another good band i havnt mentioned, the drumming is insane, listen to
"What is In the making"
my favorite song, the drumming is ridiculous half way in, try to listen to all of the tracks if you can, but definitely listen to this one.
http://www.myspace.com/neilperrynoise