Our DPS is actually better with these changes, especially on trash.
Keep in mind several things:
1. Avenger's Shield scales better than SoT. I was getting 126k HITS out of it at high vengeance (~35k AP bonus). And that's on 3 targets, it's absurd. It also scales better than Holy Wrath.
2. 5-mans are fine because of the above. Even with little to no Vengeance, Avenger's Shield still hits hard. If your Feral druid is still pulling aggro off you, he's attacking too soon. If you REALLY want to hold aggro on trash packs, try casting Holy Prism on yourself once the mobs are in range of you. It'll zap 5 of them for ~28k with NO vengeance at all, more with vengeance. It's some pretty good burst threat.
Like I said, I'm not 90 yet, so no Holy Prism. :P
My friend pulling off of me was kind of impossible to prevent as long as he wasn't holding back (which he shouldn't have to). When I'm doing 12k DPS and he's bursting 60-70k, not even the 500% threat boost will allow me to out-threat him during those burst periods (which on a five-man boss can be most of the fight).
I won't make a real judgment on it until 90, but I really do hope it feels better than it did at 85. It's mostly the discrepancy between tank damage and DPS damage that was problematic, which I hope will be solved by the stat decay from leveling and no longer being final-tier-geared...but then, our DPS scaling from gear grinds to a halt at 90 due to the new Vengeance model, so as the expansion progresses our threat in five-mans will get worse and worse as DPS damage improves and ours doesn't. But I guess Blizzard can address that when it happens.
EDIT: I think my wave of indignant anger has passed now. :O I do trust that the devs know what they're doing, so I'm hopeful that my fears will prove ungrounded, or that they'll be fixed if they come true.