I would say the main reason you feel that way is probably b/c more or less, one guy (D-Sane) makes the beats for SLR. Also I think that is more the way the old SLR (FTS) sounded. The new SLR is not that way, Lac of Respect has 4 guys all with very distinctive voices and very distinctive styles. The 2 guys in Dividenz have very distinctive voices, Crytical kind of reminds me of the older SLR guys but better b/c he can break into a sing too.
I see what you're saying though. And I'd say it doesn't have much to do w/ Seattle, more to do with SLR.