I just balk at the idea... multiple limbs is one thing, SICK physical stats is another.  But primarily, I'm hesitant to say 'yes' because they're so... er... giant insect-like?  I guess that's one of the most interesting things about playing with a group in a homebrew-ish setting... you really have no clue what people are going to want to do.  I can kind of imagine thri-kreen working, but I had never even considered them when envisioning this world.  For some reason, when I thought of the element of "the other"-- the alien races that the colonists encounter and judge, investigate, struggle to understand-- I didn't envision giant intelligent insects.<br/><br/>I'm not going to rule it out YET, but think about that sense of cultural unity and familial association from other perspectives as well... certain elements of society can be explored with any fantasy species.