Well if you go by the TNG tech manual, I suspect settings 4 thu 6 will sting a little.
From memory in the 24th century
settings 1-3 are the stun settings fromm light to eavy
Settings 4-6 cause thermal damage.
Setting 7 effectively kills
Setting 8 is vaporise
Settings 9-16 are only availble on Type II and Type III rifles
By which time you are getting into melting metals, destroying rock, possible penetration of shields etc...
I was under the impression that 1-8 = stun and 9-16 = kill.