I have run several tests on my own, with a friend. Loot is still hardbto gauge because it's still pretty much bad all around, but rep is definitely reduced. Around level 17 sailing we started running these tests, on EITC Ogres. If I engaged, battled, and defeated the ship on my own, without any outside interference, I received approximately 138 rep, give or take. Then we proceeded to have him fire one broadside in the ship before it sank, and it reduced me to about 115 rep a ship. When he engaged, and actually battled the ships I did, I got around 90-95 rep. I know, I'm not a dev, but I have extensively put this to the test. Again, loot is still really bad so, it's hard to tell if it's affected, but I can say with certainty, that rep is, simply due to the fact, that rep is totaled by the number of hits. If someone comes along, fights the ship, and helps sink it, naturally you get less hits, and less rep.