Are Jehovah's Witnesses people of Integrity? The short answer to this is YES. Jehovah's Witnesses are some of the most loyal people around.
No. Loyalty and integrity are not synonymous.
You began with this:
I think of individuals grounded in principles, who do not operate on opinions that change based on the breeze of political or social change. A life that is directed by a code of morality, not on capricious emotions.
By those standards alone JWs fail the test of integrity BECAUSE they are blindly obedient (what you call "loyalty") to the GB.