Yeah, DB's been about on par with slayers, up to the point I leveled it (20, then promptly switched over to demonologist), t'me. Playing about the same, roughly the same degree of toughness (once you hit 12), similar damage output (i.e. overkill until past the west).
Demonologists are... different. Playing it, not entirely sure I
like it. Hoping things get more interesting as the higher tier seeds show up, since you really kinda' need 'em to use and sustain much of your talents. Need that vim on hit/getting hit, et al. Right now (level 16, in nur) they're just kinda' awkward feeling. Doing alright, outside of eating a death from running into three ooze horrors and a pack of luminious (and not dipping before running out of the resources needed to power my escape methods. Round two went much more smoothly.), all at the same time, though. Biggest problem for them is probably vim regeneration at low-ish levels -- if they're having trouble killing something, there's not much they can do mid-fight if their vim taps out (unless you get that locked tier 3 talent, which instead buggers your stamina right into the ground). I expect that to change when I've got better seeds, but for the time being it's a PitA

E: Ohey, they updated.
Demonologist and
doombringer. Ignore the blood knight addon -- there's some kind of annoying bug where the bloody game won't load without the freaking thing active. And I'm too lazy to fix it, since it doesn't really meaningfully change the game outside of adding a class and improving the bleed status UI. Demo's gained a level since then, though.