1) improve tank base dps to 8-10k
this can easily be done by converting 1H&S to health based and putting a bleed dot on heroic slash.
2) slightly improve healer dps capability to 10-15k. This can be best done through the restoration line by adding in empower for critical heals and or cost reduction for the next destruction line dmging skill.
these are simple changes to bring up base group dps to make the groupfinder a more successful experience especially for poor dps groups. This also might increase the number of tank players which would also improve the experience.
i wont go into required dps role changes because everyone gets their back up.